Chapter 1: Data Converter History ........................................................................................3
Section 1-1: Early History .............................................................................................................5
The Early Years: Telegraph to Telephone .......................................................................................... 6
The Invention of PCM ....................................................................................................................... 8
The Mathematical Foundations of PCM ........................................................................................... 9
The PCM Patents of Alec Harley Reeves ........................................................................................ 10
PCM and the Bell System: World War II through 1948 .................................................................. 11
Op Amps and Regenerative Repeaters: Vacuum Tubes to Solid-State ............................................ 13
Section 1-2: Data Converters of the 1950s and 1960s ...................................................................19
Commercial Data Converters: 1950s ............................................................................................... 19
Commercial Data Converter History: 1960s ................................................................................... 20
Data Converter Architectures .......................................................................................................... 23
Section 1-3: Data Converters of the 1970s ...................................................................................27
Monolithic Data Converters of the 1970s ........................................................................................28
Bipolar Process IC DACs of the 1970s ...........................................................................................28
CMOS IC DACs of the 1970s ......................................................................................................... 29
Monolithic ADCs of the 1970s ........................................................................................................ 31
Hybrid Data Converters of the 1970s .............................................................................................. 32
Modular Data Converters of the 1970s ............................................................................................ 35
Section 1-4: Data Converters of the 1980s ...................................................................................39
Monolithic DACs of the 1980s ........................................................................................................ 40
Monolithic ADCs of the 1980s ........................................................................................................ 41
Monolithic Flash ADCs of the 1980s .............................................................................................. 42
Hybrid and Modular DACs and ADCs of the 1980s ....................................................................... 42
Section 1-5: Data Converters of the 1990s ...................................................................................45
Monolithic DACs of the 1990s ........................................................................................................ 46
Monolithic ADCs of the 1990s ........................................................................................................ 48
Hybrid and Modular DACs and ADCs of the 1990s ....................................................................... 52
Section 1-6: Data Converters of the 2000s ...................................................................................53
Chapter 2: Fundamentals of Sampled Data Systems ...............................................................57
Section 2-1: Coding and Quantizing .............................................................................................57
Unipolar Codes ................................................................................................................................ 59
Gray Code ........................................................................................................................................ 61
Bipolar Codes .................................................................................................................................. 62
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Complementary Codes .................................................................................................................... 65
DAC and ADC Static Transfer Functions and DC Errors ............................................................... 66
Section 2-2: Sampling Theory ......................................................................................................73
The Need for a Sample-and-Hold Amplifi er (SHA) Function ........................................................ 74
The Nyquist Criteria ........................................................................................................................ 76
Baseband Antialiasing Filters .......................................................................................................... 78
Undersampling (Harmonic Sampling, Bandpass Sampling, IF Sampling,
Direct IF-to-Digital Conversion) ................................................................................................. 80
Antialiasing Filters in Undersampling Applications ....................................................................... 81
Section 2-3: Data Converter AC Errors ........................................................................................83
Theoretical Quantization Noise of an Ideal N-Bit Converter .......................................................... 83
Noise in Practical ADCs .................................................................................................................. 88
Equivalent Input Referred Noise .................................................................................................... 89
Noise-Free (Flicker-Free) Code Resolution ................................................................................... 89
Dynamic Performance of Data Converters ...................................................................................... 90
Integral and Differential Nonlinearity Distortion Effects ................................................................ 90
Harmonic Distortion, Worst Harmonic, Total Harmonic Distortion (THD),
Total Harmonic Distortion Plus Noise (THD + N) ...................................................................... 91
Signal-to-Noise-and-Distortion Ratio (SINAD), Signal-to-Noise Ratio (SNR),
and Effective Number of Bits (ENOB) ....................................................................................... 91
Analog Bandwidth ........................................................................................................................... 92
Spurious Free Dynamic Range (SFDR) .......................................................................................... 93
Two-Tone Intermodulation Distortion (IMD) ................................................................................. 94
Second- and Third-Order Intercept Points, 1 dB Compression Point ............................................. 95
Multitone Spurious Free Dynamic Range ....................................................................................... 96
Wideband CDMA (WCDMA) Adjacent Channel Power Ratio (ACPR) and Adjacent
Channel Leakage Ratio (ADLR) ................................................................................................. 97
Noise Power Ratio (NPR) ................................................................................................................ 98
Noise Factor (F) and Noise Figure (NF) ....................................................................................... 100
Aperture Time, Aperture Delay Time, and Aperture Jitter ........................................................... 106
A Simple Equation for the Total SNR of an ADC ........................................................................ 108
ADC Transient Response and Overvoltage Recovery ................................................................... 109
ADC Sparkle Codes, Metastable States, and Bit Error Rate (BER) ............................................. 111
DAC Dynamic Performance ......................................................................................................... 115
DAC Settling Time ................................................................................................................. 115
Glitch Impulse Area ............................................................................................................... 116
DAC SFDR and SNR ............................................................................................................. 117
Measuring DAC SNR with an Analog Spectrum Analyzer .................................................... 118
DAC Output Spectrum and sin (x)/x Frequency Roll-off ....................................................... 119
Oversampling Interpolating DACs ......................................................................................... 120
Section 2-4: General Data Converter Specifi cations ......................................................................123
Overall Considerations .................................................................................................................. 123
Logic Interface Issues .................................................................................................................... 124
Data Converter Logic: Timing and other Issues ............................................................................ 125
Section 2-5: Defi ning the Specifi cations .......................................................................................127
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Chapter 3: Data Converter Architectures ............................................................................147
Section 3-1: DAC Architectures .................................................................................................147
DAC Output Considerations .......................................................................................................... 148
Basic DAC Structures .................................................................................................................... 149
The Kelvin Divider (String DAC) .......................................................................................... 149
Thermometer (Fully-Decoded) DACs .................................................................................... 151
Binary-Weighted DACs .......................................................................................................... 153
R-2R DACs ............................................................................................................................. 155
Segmented DACs .................................................................................................................... 159
Oversampling Interpolating DACs ................................................................................................ 163
Multiplying DACs ......................................................................................................................... 164
Intentionally Nonlinear DACs ....................................................................................................... 164
Counting, Pulsewidth-Modulated (PWM) DACs .......................................................................... 167
Cyclic Serial DACs ........................................................................................................................ 167
Other Low Distortion Architectures .............................................................................................. 169
DAC Logic Considerations ............................................................................................................ 170
Section 3-2: ADC Architectures .................................................................................................175
The Comparator: A 1-Bit ADC ...................................................................................................... 178
High Speed ADC Architectures ..................................................................................................... 180
Flash Converters ..................................................................................................................... 180
Successive Approximation ADCs ........................................................................................... 185
Subranging, Error Corrected, and Pipelined ADCs ............................................................... 190
Serial Bit-Per-Stage Binary and Gray Coded (Folding) ADCs ............................................. 203
Counting and Integrating ADC Architectures ............................................................................... 211
A. H. Reeves’ 5-Bit Counting ADC ....................................................................................... 211
Charge Run-Down ADC ......................................................................................................... 212
Ramp Run-Up ADC ............................................................................................................... 212
Tracking ADC ........................................................................................................................ 213
Voltage-to-Frequency Converters (VFCs) .............................................................................. 214
Dual Slope/Multislope ADCs ................................................................................................. 218
Optical Converters ......................................................................................................................... 220
Resolver-to-Digital Converters (RDCs) and Synchros .................................................................. 221
Section 3-3: Sigma-Delta Converters ..........................................................................................231
Historical Perspective .................................................................................................................... 231
Sigma-Delta (Σ-∆) or Delta-Sigma (∆-Σ)? ................................................................................... 234
Basics of Sigma-Delta ADCs ........................................................................................................ 235
Idle Tone Considerations ............................................................................................................... 240
Higher Order Loop Considerations ............................................................................................... 241
Multibit Sigma-Delta Converters .................................................................................................. 242
Digital Filter Implications ............................................................................................................. 243
Multistage Noise Shaping (MASH) Sigma-Delta Converters ....................................................... 244
High Resolution Measurement Sigma-Delta ADCs ...................................................................... 245
Sigma-Delta DACs ........................................................................................................................ 249
Chapter 4: Data Converter Process Technology ....................................................................257
Section 4-1: Early Processes ......................................................................................................257
Vacuum Tube Data Converters ...................................................................................................... 257
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Solid State, Modular, and Hybrid Data Converters ....................................................................... 259
Calibration Processes ..................................................................................................................... 262
Section 4-2: Modern Processes ...................................................................................................265
Bipolar Processes ........................................................................................................................... 265
Thin Film Resistor Processes ........................................................................................................ 265
Complementary Bipolar (CB) Processes ....................................................................................... 266
CMOS Processes ........................................................................................................................... 266
Data Converter Processes and Architectures ................................................................................. 268
Section 4-3: Smart Partitioning .................................................................................................273
When Complete Integration Isn’t the Optimal Solution ................................................................ 273
Why Smart Partitioning is Necessary ........................................................................................... 276
What’s Changing? ......................................................................................................................... 277
Chapter 5: Testing Data Converters ...................................................................................283
Section 5-1: Testing DACs ........................................................................................................283
Static DAC Testing ........................................................................................................................ 283
End-Point Errors ..................................................................................................................... 284
Linearity Errors ...................................................................................................................... 286
Superposition and DAC Errors ............................................................................................... 286
Measuring DAC DNL and INL Using Superposition ............................................................ 287
Measuring DAC INL and DNL Where Superposition Does Not Hold .................................. 290
Testing DACs for Dynamic Performance ...................................................................................... 292
Settling Time .......................................................................................................................... 292
Glitch Impulse Area ............................................................................................................... 293
Oscilloscope Measurement of Settling Time and Glitch Impulse Area ................................ 294
Distortion Measurements ....................................................................................................... 295
Section 5-2: Testing ADCs ........................................................................................................303
A Brief Historical Overview of Data Converter Specifi cations and Testing ................................. 303
Static ADC Testing ........................................................................................................................ 304
Back-to-Back Static ADC Testing .......................................................................................... 306
Crossplot Measurements of ADC Linearity ........................................................................... 309
Servo-Loop Code Transition Test ........................................................................................... 310
Computer-Based Servo-Loop ADC Tester ............................................................................. 311
Histogram (Code Density) Test with Linear Ramp Input ...................................................... 312
Dynamic ADC Testing ................................................................................................................... 317
Manual “Back-to-Back” Dynamic ADC Testing ................................................................... 317
Measuring Effective Number of Bits (ENOB) Using Sinewave Curve Fitting ...................... 320
FFT Basics .............................................................................................................................. 322
FFT Test Setup Confi guration and Measurements ................................................................. 329
Verifying the FFT Accuracy ................................................................................................... 335
Generating Low Distortion Sinewave Inputs ......................................................................... 335
Noise Power Ratio (NPR) Testing .......................................................................................... 337
Measuring ADC Aperture Jitter Using the Locked-Histogram Test Method ......................... 338
Measuring Aperture Delay Time ............................................................................................ 340
Measuring ADC Aperture Jitter Using FFTs .......................................................................... 340
Measuring ADC Analog Bandwidth Using FFTs .................................................................. 342
Settling Time .......................................................................................................................... 343
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Overvoltage Recovery Time ................................................................................................... 344
Video Testing, Differential Gain and Differential Phase ........................................................ 344
Bit Error Rate (BER) Tests ..................................................................................................... 348
Chapter 6: Interfacing to Data Converters ...........................................................................359
Section 6-1: Driving ADC Analog Inputs .....................................................................................359
Amplifer DC and AC Performance Considerations ...................................................................... 361
Rail-Rail Input Stages .................................................................................................................... 362
Output Stages ................................................................................................................................. 365
Gain and Level-Shifting Circuits Using Op Amps ........................................................................ 367
Op Amp AC Specifi cations and Data Converter Requirements .................................................... 369
Driving High Resolution Σ-∆ Measurement ADCs ....................................................................... 371
Driving Single-Ended Input Single-Supply 1.6 V to 3.6 V Successive Approximation ADCs ..... 372
Driving Single-Supply ADCs with Scaled Inputs ......................................................................... 373
Driving Differential Input CMOS Switched Capacitor ADCs ...................................................... 374
Single-Ended Drive Circuits for Differential Input CMOS ADCs ................................................ 376
Differential Input ADC Drivers ..................................................................................................... 378
Driving ADCs with Differential Amplifi ers .................................................................................. 382
Dual Op Amp Drivers .................................................................................................................... 383
Fully Integrated Differential Amplifi er Drivers ............................................................................. 384
Driving Differential Input ADCs with Integrated Differential Drivers ......................................... 387
Section 6-2: ADC and DAC Digital Interfaces(and Related Issues) ................................................397
Power-On Initialization of Data Converters ................................................................................. 397
Initialization of Data Converter Internal Control Registers ........................................................... 398
Low Power, Sleep, and Standby Modes ....................................................................................... 398
Single-Shot Mode, Burst Mode, and Minimum Sampling Frequency .......................................... 399
ADC Digital Output Interfaces ...................................................................................................... 400
ADC Serial Output Interfaces ....................................................................................................... 400
ADC Serial Interface to DSPs ...................................................................................................... 403
ADC Parallel Output Interfaces ..................................................................................................... 405
DAC Digital Input Interfaces ......................................................................................................... 408
DAC Serial Input Interfaces to DSPs ............................................................................................ 410
DAC Parallel Input Interfaces to DSPs .......................................................................................... 411
Section 6-3: Buffering DAC Analog Outputs ...............................................................................415
Differential to Single-Ended Conversion Techniques ................................................................... 416
Single-Ended Current-to-Voltage Conversion ............................................................................... 418
Differential Current-to-Differential Voltage Conversion ............................................................... 420
An Active Low-Pass Filter for Audio DAC .................................................................................. 420
Section 6-4: Data Converter Voltage References ..........................................................................423
Section 6-5: Sampling Clock Generation .....................................................................................427
Oscillator Phase Noise and Jitter ................................................................................................... 430
“Hybrid” Clock Generators ........................................................................................................... 437
Driving Differential Sampling Clock Inputs ................................................................................. 438
Sampling Clock Summary ............................................................................................................. 439
Chapter 7: Data Converter Support Circuits ........................................................................443
Section 7-1: Voltage References .................................................................................................443
Precision Voltage References ........................................................................................................ 443
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Types of Voltage References .......................................................................................................... 444
Bandgap References ............................................................................................................... 446
Buried Zener References ........................................................................................................ 451
XFET References ................................................................................................................... 452
Voltage Reference Specifi cations .................................................................................................. 455
Tolerance ................................................................................................................................ 455
Drift ........................................................................................................................................ 455
Supply Range ......................................................................................................................... 456
Load Sensitivity ...................................................................................................................... 456
Line Sensitivity ....................................................................................................................... 457
Noise ....................................................................................................................................... 457
Scaled References .......................................................................................................................... 459
Voltage Reference Pulse Current Response ................................................................................... 460
Low Noise References for High Resolution Converters ............................................................... 462
Section 7-2: Low Dropout Linear Regulators ...............................................................................465
Linear Voltage Regulator Basics .................................................................................................... 465
Pass Devices and their Associated Trade Offs ............................................................................... 468
Low Dropout Regulator Architectures .......................................................................................... 472
The anyCAP Low Dropout Regulator Family ............................................................................... 475
Design Features Related to DC Performance ......................................................................... 475
Design Features Related to AC Performance ......................................................................... 476
A Basic Pole-Splitting Topology ............................................................................................ 477
The anyCAP Pole-Splitting Topology .................................................................................... 477
The anyCAP LDO series devices ........................................................................................... 478
Functional Diagram and Basic 50 mA LDO Regulator ......................................................... 479
LDO Regulator Thermal Considerations ............................................................................... 481
LDO Regulator Controllers ........................................................................................................... 485
Regulator Controller Differences ........................................................................................... 485
A Basic 5 V/1 A LDO Regulator Controller .......................................................................... 486
Selecting the Pass Device ....................................................................................................... 487
Thermal Design ...................................................................................................................... 488
Sensing Resistors for LDO Controllers .................................................................................. 489
PCB Layout Issues ................................................................................................................. 490
A 2.8 V/8 A LDO Regulator Controller ................................................................................. 491
Section 7-3: Analog Switches and Multiplexers ............................................................................493
CMOS Switch Basics .................................................................................................................... 494
Error Sources in the CMOS Switch ............................................................................................... 496
Applying the Analog Switch ........................................................................................................ 504
1 GHz CMOS Switches ................................................................................................................. 508
Video Switches and Multiplexers .................................................................................................. 508
Video Crosspoint Switches ............................................................................................................ 511
Digital Crosspoint Switches .......................................................................................................... 512
Switch and Multiplexer Families from Analog Devices ................................................................ 512
Parasitic Latchup in CMOS Switches and Muxes ......................................................................... 512
Section 7-4: Sample-and-Hold Circuits ........................................................................................519
Introduction and Historical Perspective ........................................................................................ 519
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Basic SHA Operation .................................................................................................................... 521
Track Mode Specifi cations ............................................................................................................ 522
Track-to-Hold Mode Specifi cations .............................................................................................. 522
Hold Mode Specifi cations ............................................................................................................. 526
Hold-to-Track Transition Specifi cations ....................................................................................... 528
SHA Architectures ......................................................................................................................... 529
Internal SHA Circuits for IC ADCs ............................................................................................... 531
SHA Applications .......................................................................................................................... 533
Chapter 8: Data Converter Applications .............................................................................539
Section 8-1: Precision Measurement and Sensor Conditioning ........................................................539
Applications of Precision Measurement Σ-∆ ADCs ...................................................................... 540
Weigh Scale Design Analysis Using the AD7730 ADC ................................................................ 544
Thermocouple Conditioning Using the AD7793 ........................................................................... 549
Direct Digital Temperature Measurements .................................................................................... 551
Microprocessor Substrate Temperature Sensors ............................................................................ 555
Applications of ADCs in Power Meters ........................................................................................ 558
Section 8-2: Multichannel Data Acquisition Systems .....................................................................563
Data Acquisition System Confi gurations ....................................................................................... 563
Multiplexing .................................................................................................................................. 564
Filtering Considerations in Data Acquisition Systems .................................................................. 567
Complete Data Acquisition Systems on a Chip ............................................................................. 568
Multiplexing Inputs to Σ-∆ ADCs ................................................................................................. 570
Simultaneous Sampling Systems ................................................................................................... 572
Data Distribution Systems ............................................................................................................ 574
Data Distribution Using an Infi nite Sample-and-Hold .................................................................. 578
Section 8-3: Digital Potentiometers ............................................................................................581
Modern Digital Potentiometers in Tiny Packages ......................................................................... 582
Digital Potentiometers with Nonvolatile Memory ........................................................................ 584
One-Time Programmable (OTP) Digital Potentiometers .............................................................. 585
Digital Potentiometer AC Considerations ..................................................................................... 586
Application Examples ................................................................................................................... 587
Section 8-4: Digital Audio .........................................................................................................591
Sampling Rate and THD + N Requirements for Digital Audio ..................................................... 592
Overall Trends in Digital Audio ADCs and DACs ........................................................................ 595
Voiceband Codecs .......................................................................................................................... 596
High Performance Audio ADCs and DACs in Separate Packages ................................................ 597
High Performance Multichannel Audio Codecs and DACs .......................................................... 600
Sample Rate Converters ................................................................................................................ 602
Section 8-5: Digital Video and Display Electronics .......................................................................607
Digital Video .................................................................................................................................. 607
Digital Video Formats ............................................................................................................ 608
Serial Data Interfaces ............................................................................................................. 612
Digital Video ADCs and DACs: Decoders, and Encoders ..................................................... 612
Specifi cations for Video Decoders and Encoders ................................................................... 614
Display Electronics ........................................................................................................................ 615
Flat Panel Display Electronics ............................................................................................... 619
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CCD Imaging Electronics ...................................................................................................... 622
Touchscreen Digitizers ........................................................................................................... 627
Section 8-6: Software Radio and IF Sampling ..............................................................................633
Evolution of Software Radio ......................................................................................................... 634
A Receiver Using Digital Processing at Baseband ........................................................................ 635
Narrowband IF-Sampling Digital Receivers ................................................................................. 636
Wideband IF-Sampling Digital Receivers ..................................................................................... 639
Increasing ADC Dynamic Range Using Dither ............................................................................. 649
Wideband Radio Transmitter Considerations ................................................................................ 655
Cellular Telephone Handsets ......................................................................................................... 659
The Role of ADCs and DACs in Cellular Telephone Handsets ..................................................... 661
SoftFone® and Othello Radio Chipsets from Analog Devices ..................................................... 662
Time-Interleaved IF Sampling ADCs with Digital Post-Processors ............................................. 667
Advanced Digital Post Processing ................................................................................................. 671
Advanced Filter Bank (AFB) ........................................................................................................ 672
AFB Design Example: The AD12400 12-Bit, 400 MSPS ADC ................................................... 673
Section 8-7: Direct Digital Synthesis (DDS) ................................................................................677
Introduction to DDS ...................................................................................................................... 677
Aliasing in DDS Systems .............................................................................................................. 681
Frequency Planning in DDS Systems ............................................................................................ 682
Modern Integrated DDS Systems .................................................................................................. 684
Section 8-8: Precision Analog Microcontrollers ............................................................................693
Characteristics of the MicroConverter Product Family ................................................................. 694
Some Σ-∆ MicroConverter Applications ....................................................................................... 700
ADuC7xxx MicroConverter Products Based on the ARM7 Processor Core ................................ 702
Chapter 9: Hardware Design Techniques .............................................................................709
Section 9-1: Passive Components ...............................................................................................711
Capacitors ...................................................................................................................................... 711
Dielectric Absorption ............................................................................................................. 712
Capacitor Parasitics and Dissipation Factor ........................................................................... 714
Tolerance, Temperature, and Other Effects ............................................................................ 715
Assemble Critical Components Last ...................................................................................... 715
Resistors and Potentiometers ......................................................................................................... 718
Resistor Parasitics ................................................................................................................... 720
Thermoelectric Effects ........................................................................................................... 720
Voltage Sensitivity, Failure Mechanisms, and Aging ............................................................. 722
Resistor Excess Noise ............................................................................................................ 723
Potentiometers ........................................................................................................................ 723
Inductance ...................................................................................................................................... 725
Stray Inductance ..................................................................................................................... 725
Mutual Inductance .................................................................................................................. 725
Ringing ................................................................................................................................... 728
Parasitic Effects in Inductors .................................................................................................. 728
Q or “Quality Factor” ............................................................................................................. 729
Don’t Overlook Anything .............................................................................................................. 729
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Section 9-2: PC Board Design Issues ..........................................................................................733
Resistance of Conductors .............................................................................................................. 733
Voltage Drop in Signal Leads—“Kelvin” Feedback ..................................................................... 735
Signal Return Currents .................................................................................................................. 736
Grounding in Mixed Analog/Digital Systems ............................................................................... 737
Ground and Power Planes ...................................................................................................... 738
Double-Sided versus Multilayer Printed Circuit Boards ........................................................ 739
Multicard Mixed-Signal Systems ........................................................................................... 740
Separating Analog and Digital Grounds ................................................................................. 740
Grounding and Decoupling Mixed-Signal ICs with Low Digital Currents ........................... 742
Treat the ADC Digital Outputs with Care .............................................................................. 743
Sampling Clock Considerations ............................................................................................. 744
The Origins of the Confusion about Mixed-Signal Grounding: Applying Single-Card
Grounding Concepts to Multicard Systems ...................................................................... 746
Summary: Grounding Mixed-Signal Devices with Low Digital Currents in a
Multicard System ............................................................................................................... 747
Summary: Grounding Mixed-Signal Devices with High Digital Currents in a
Multicard System ............................................................................................................... 748
Grounding DSPs with Internal Phase-Locked Loops ............................................................. 748
Grounding Summary .............................................................................................................. 749
Some General PC Board Layout Guidelines for Mixed-Signal Systems ...................................... 750
Skin Effect .............................................................................................................................. 751
Transmission Lines ................................................................................................................. 753
Be Careful With Ground Plane Breaks ................................................................................... 753
Ground Isolation Techniques .................................................................................................. 754
Static PCB Effects .................................................................................................................. 756
Sample MINIDIP and SOIC Op Amp PCB Guard Layouts .................................................. 758
Dynamic PCB Effects ............................................................................................................ 760
Stray Capacitance ................................................................................................................... 761
Capacitive Noise and Faraday Shields ................................................................................... 762
The Floating Shield Problem .................................................................................................. 762
Buffering ADCs Against Logic Noise ................................................................................... 763
Section 9-3: Analog Power Supply Systems ..................................................................................767
Linear IC Regulation ..................................................................................................................... 768
Some Linear Voltage Regulator Basics .................................................................................. 768
Pass Devices .......................................................................................................................... 770
±15 V Regulator Using Adjustable Voltage ICs ..................................................................... 770
Low Dropout Regulator Architectures ................................................................................... 771
Fixed-Voltage, 50/100/200/500/1000/1500 mA LDO Regulators ......................................... 772
Adjustable Voltage, 200 mA LDO Regulator ......................................................................... 774
Charge-Pump Voltage Converters ................................................................................................. 775
Regulated Output Charge-Pump Voltage Converters .................................................................... 776
Linear Post Regulator for Switching Supplies .............................................................................. 778
Grounding Linear and Switching Regulators ................................................................................ 779
Power Supply Noise Reduction and Filtering ............................................................................... 782
Capacitors ............................................................................................................................... 782
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Contents
Ferrites .................................................................................................................................... 786
Card Entry Filter ..................................................................................................................... 787
Rail Bypass/Distribution Filter ............................................................................................... 788
Local High Frequency Bypass/Decoupling ............................................................................ 789
Section 9-4: Overvoltage Protection ...........................................................................................793
In-Circuit Overvoltage Protection ................................................................................................. 793
General Input Common Mode Limitations ................................................................................... 793
Clamping Diode Leakage .............................................................................................................. 795
A Flexible Voltage Follower Protection Circuit ........................................................................... 796
Common-Mode Overvoltage Protection Using CMOS Channel Protectors ................................. 797
CM Overvoltage Protection Using High CM Voltage In Amp ...................................................... 798
Inverting Mode Op Amp Protection Schemes ............................................................................... 800
Amplifi er Output Voltage Phase-Reversal ..................................................................................... 800
An Output Phase-Reversal Do-it-Yourself Test ...................................................................... 802
Fixes for Output Phase–Reversal ........................................................................................... 802
Input Differential Protection ......................................................................................................... 803
Protecting In Amps Against Overvoltage ...................................................................................... 804
Overvoltage Protection Using CMOS Channel Protectors ............................................................ 808
Digital Isolators ............................................................................................................................. 810
Out-of-Circuit Overvoltage Protection .......................................................................................... 813
ESD Models and Testing ............................................................................................................... 817
Section 9-5: Thermal Management .............................................................................................823
Thermal Basics .............................................................................................................................. 823
Heat Sinking .................................................................................................................................. 825
Data Converter Thermal Considerations ....................................................................................... 829
Section 9-6: EMI/RFI Considerations .........................................................................................833
EMI/RFI Mechanisms ................................................................................................................... 834
EMI Noise Sources ........................................................................................................................ 834
EMI Coupling Paths ...................................................................................................................... 834
Noise Coupling Mechanisms ......................................................................................................... 834
Reducing Common-Impedance Noise ........................................................................................... 835
Noise Induced by Near-Field Interference .................................................................................... 836
Reducing Capacitance-Coupled Noise .......................................................................................... 836
Reducing Magnetically-Coupled Noise ........................................................................................ 837
Passive Components: Your Arsenal Against EMI .......................................................................... 838
Reducing System Susceptibility to EMI ........................................................................................ 839
A Review of Shielding Concepts ................................................................................................... 839
General Points on Cables and Shields ........................................................................................... 842
Input-Stage RFI Rectifi cation Sensitivity ...................................................................................... 846
Background: Op Amp and In Amp RFI Rectifi cation Sensitivity Tests ................................. 846
An Analytical Approach: BJT RFI Rectifi cation .................................................................... 847
An Analytical Approach: FET RFI Rectifi cation .................................................................. 848
Reducing RFI Rectifi cation Within Op amp and In Amp Circuits ......................................... 849
Op Amp Inputs ............................................................................................................................. 849
In Amp Inputs ................................................................................................................................ 850
Amplifi er Outputs and EMI/RFI ................................................................................................... 852
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Contents
Printed Circuit Board Design for EMI/RFI Protection .................................................................. 852
Choose Logic Devices Carefully .................................................................................................. 853
Design PCBs Thoughtfully ............................................................................................................ 853
Designing Controlled Impedances Traces on PCBs ..................................................................... 854
Microstrip PCB Transmission Lines ............................................................................................. 855
Some Microstrip Guidelines .......................................................................................................... 855
Symmetric Stripline PCB Transmission Lines .............................................................................. 856
Some Pros and Cons of Embedding Traces ................................................................................... 857
Dealing with High-Speed Logic .................................................................................................... 858
Section 9-7: Low Voltage Logic Interfacing ..................................................................................867
Voltage Tolerance and Voltage Compliance .................................................................................. 870
Interfacing 5 V Systems to 3.3 V Systems using NMOS FET “Bus Switches” ............................ 871
3.3 V/2.5 V Interfaces .................................................................................................................... 873
3.3 V/2.5 V, 3.3 V/1.8 V, 2.5 V/1.8 V Interfaces ............................................................................ 874
Hot Swap and Hot Plug Applications of Bus Switches ................................................................. 878
Internally Created Voltage Tolerance / Compliance ...................................................................... 879
Section 9-8: Breadboarding and Prototyping ...............................................................................881
“Deadbug” Prototyping ................................................................................................................. 882
Solder-Mount Prototyping ............................................................................................................. 884
Milled PCB Prototyping ................................................................................................................ 885
Beware of Sockets ......................................................................................................................... 886
Some Additional Prototyping Points ............................................................................................. 887
Evaluation Boards .......................................................................................................................... 887
General-Purpose Op Amp Evaluation Board from the Mid-1990s ........................................ 888
Dedicated Op Amp Evaluation Boards .................................................................................. 888
Data Converter Evaluation Boards ......................................................................................... 890
Index ...............................................................................................................................895
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