This document discusses behavioral modeling and Analog Devices' approach to modeling analog-to-digital converters. It introduces ADIsimADC, Analog Devices' free behavioral modeling tool for high-speed ADCs. The presentation explains why behavioral modeling is useful, how it models converter behavior through proxies without simulating internal circuitry, and what capabilities ADIsimADC currently offers. It envisions expanding ADIsimADC to support more products and accurate modeling features in the future.

1. The World Leader in High Performance Signal Processing Solutions
Converter Simulation – Beyond
the Evaluation Board
Analog Devices’ Approach to Behavioral Modeling
By: Tom MacLeod

2. Outline
 Modeling Overview
 Who am I?
 What is Converter Simulation?
 Why Model at All?
 How Does One Model Behavior?
 How Does One Model Converter Behavior?
 Modeling Converter Behavior
 Can behavioral modeling be any good?
 What can converter modeling do for me?
 Does Analog Devices currently have a converter modeling tool?
 What is the Future for Behavioral Modeling?
 Review
 Q&A
2

3. Who am I?
 My name is Tom MacLeod
 Applications/Software Engineer for the Converter System
Applications group
 Developer of ADIsimADC™
 Developer of Tools/Scripts for the lab
 Traditional Applications for High Speed ADCs
 Been with ADI for 7.578 years
 Graduated from North Carolina State University

4. What is Converter Simulation?
 Itis a “top down” or “black box” approach to modeling a
converter (inherently a mixed signal device)
 It models the “what” as opposed to the “how”
 Models the transfer function rather than multi-stage pipeline
 Models harmonic distortion rather than transistor imbalance within
a current mirror of an input buffer
 Itimplements a unique strategy, modeling characteristics of
interest (proxies) without needing to know the circuit level
implementation

5. What is Converter Simulation? (cont.)
 The
concept of modeling converter proxies generalizes to a
modeling philosophy known as “behavioral modeling”
 BehavioralModeling – the ability to model apparent behavior of a
process or entity without simulating the complex internal
subsystems which yield such behavior
 Example: IBIS (Input Output Buffer Information Specification ) Models
 IBIS is a method of providing information about the input/output buffers of
an integrated circuit to the outside world. It is an EIA (Electronic Industries
Alliance) standard. The idea of IBIS is to provide the behavioral aspects
of a circuit without providing the actual circuit information to the
user. – Wikipedia
 Models:
 Current vs. Voltage
 Voltage vs. Time

6. What is Converter Simulation? (cont.)
 What behavioral modeling is not
 NotSPICE (Simulation Program with Integrated Circuit Emphasis)
 General-purpose analog electric circuit simulator
 Not a database
 Not Evaluation Software

7. Why Model at All?
 Simulation is becoming heavily used in system design and
initial characterization to reduce risk and cost
 Modeling communicates information about new products
more quickly and comprehensively than traditional means of
product introduction
 Modeling communicates information about our current
portfolio more efficiently and intuitively to the “young kids
with their iPods and videogames”

8. Why Model at All? (cont.)
 Benefits of Behavioral Modeling
 Reduces the technical complexity of the modeling tool
 Decreases simulation time
 Increases productivity and user satisfaction
 Abstracts implementation and consequently intellectual property
 Leverages reuse of modeling tool for similar products
 Can parameterize proxies thus providing a framework to support
similar products
 Simplifies model creation process
 Important when creating and maintaining hundreds of products

9. How Does One Model Behavior?
 Answer: Math Models!
 Example – Gaussian Distribution
 Example – Population Growth

10. Modeling Converter Behavior
A model should faithfully reproduce converter proxies (both
static and dynamic) such as:
 Offset
 Gain
 Quantization
 Sample Rate Dependencies
 Input Bandwidth
 Jitter Sensitivity
 Latency
 AC and DC Linearity
10

11. Modeling Converter Behavior (cont.)
 It should be flexible enough to support different architectures
 Pipeline
 Delta-Sigma
 SAR
 Support many “bolt-on” features
 Numerically Controlled Oscillators
 Digital Filters
 Noise Shapers
 Analog Filters
 Low Noise Amplifiers
 Variable Gain Amplifiers

12. Modeling Converter Behavior (cont.)
A model should be contained within a library so that it can be
called from multiple applications
 Dynamic Linked Library (DLL)

13. Can behavioral modeling be any good?
Physical
Part = AD6645
Model Model

14. Can behavioral modeling be any good? (cont.)
AD9271
(Octal LNA/VGA/AAF/ADC)
Model
Physical

15. What can converter modeling do for me?
 Live datasheet
 Find typical performance not explicitly listed on the static
datasheet
Part = AD9229, Ain = 49.3 MHz
SNR = 68 dB, 2nd = -82.8, 3rd = -80.3

16. What can converter modeling do for me? (cont.)
 Didactic
 Consider impact on performance from jitter (AN-501)
 AD9246, Ain = 2.3 MHz, fs = 125 MSPS
Calculate “composite DNL”
16

17. What can converter modeling do for me? (cont.)
 AD9246, Ain = 201.3 MHz, fs = 125 MSPS
13 fsec difference
17

18. What can converter modeling do for me? (cont.)
 Didactic
 Consider effects of adding band limited dither
Without Dither With Dither
18

19. What can converter modeling do for me? (cont.)
 Product selection
 Find
the product that meets your requirements under your
conditions
Welcome to the online ADIsimADC Design Tool
 http://www.analog.com/adisimadc
Click here

20. What can converter modeling do for me? (cont.)
Input your
requirements
(SNR > 78 dB
SFDR <= -85 dBc)
Click here
Input your
conditions

21. What can converter modeling do for me? (cont.)
Models that met
my requirements

22. What can converter modeling do for me? (cont.)
It worked!
SNR = 78 dB
SFDR = -93 dBc
What’s 100k
volume pricing?

23. What can converter modeling do for me? (cont.)
 Product Evaluation
Asubset of products (those ending in .PMF) support a register
map interface
 Example – AD6657
23

24. What can converter modeling do for me? (cont.)
 Tuning word changed from 28 to 0
 Same as real device
24

25. What can converter modeling do for me? (cont.)
 System Level Simulation
 Simulate the effects a particular ADC will have on your system
LTE Uplink (5 MHz) waveform
AD6655 (14-bit IF receiver)
SNR = 65.7 dB

26. Does Analog Devices currently have a
converter modeling tool?
 Yes - ADIsimADC
26

27. Where can I buy ADIsimADC?
 You can’t buy it! It’s free!
 Visit: http://www.analog.com/adisimadc
 As part of ADI’s “whole product initiative”
 Thereis no cost to use this tool; use it in whatever environment
you prefer
+ =

28. Where can I buy ADIsimADC? (cont.)
 We package it with VisualAnalog (also free)
Just install VisualAnalog, run it,
browse for your favorite ADC,
select it and start modeling!
Also available as an
online design tool

29. What products are currently supported?
All high speed (>20 MSPS) ADCs for the last 5 years. 188 models so far…
AD6645_105 AD9214_105_1V AD9218_80_1V AD9230_210 AD9238_20 AD9246_105 AD9255_125 AD9268_80 AD9445_105_3p2V AD9600 AD9629_40 AD80141 AD9230 AD9252 AD9287 AD9609
AD6645_80 AD9214_65_2V AD9219_40 AD9230_250 AD9238_40 AD9246_125 AD9255_80 AD9271 AD9445_125_2V AD9601 AD9629_65 AD9204 AD9231 AD9254 AD9289 AD9626
AD6655 AD9214_80_1V AD9219_65 AD9231_20 AD9238_65 AD9248_20 AD9258_105 AD9272 AD9445_125_3p2V AD9609_20 AD9629_80 AD9211 AD9233 AD9255 AD9430 AD9627-11
AD6657 AD9215_105 AD9222_40 AD9231_40 AD9239_170 AD9248_40 AD9258_125 AD9273 AD9446_100_2V AD9609_40 AD9640 AD9214 AD9236 AD9258 AD9433 AD9627
AD80141 AD9215_65 AD9222_50 AD9231_65 AD9239_210 AD9248_65 AD9258_80 AD9287 AD9446_100_3p2V AD9609_65 AD9644_80 AD9215 AD9237 AD9259 AD9444 AD9629
AD9204_20 AD9215_80 AD9222_65 AD9231_80 AD9239_250 AD9251_20 AD9259 AD9289 AD9446_80_2V AD9609_80 AD9649_20 AD9216 AD9238 AD9262 AD9445 AD9640
AD9204_40 AD9216_105 AD9226_2V AD9233_105 AD9244_40 AD9251_40 AD9262 AD9430_170_LVDS AD9446_80_3p2V AD9626_170 AD9649_40 AD9218 AD9239 AD9265 AD9446 AD9644
AD9204_65 AD9216_65 AD9228_40 AD9233_125 AD9244_65 AD9251_65 AD9265_105 AD9430_210_LVDS AD9460_105_3p4V AD9626_210 AD9649_65 AD9219 AD9244 AD9268 AD9460 AD9649
AD9204_80 AD9216_80 AD9228_65 AD9236 AD9245_20 AD9251_80 AD9265_125 AD9433_105 AD9460_80_3p4V AD9626_250 AD9649_80 AD9222 AD9245 AD9269 AD9461
AD9211_200 AD9218_105_1V AD9229_50 AD9237_20 AD9245_40 AD9252 AD9265_80 AD9433_125 AD9461_125_3p4V AD9627-11 AD6645 AD9226 AD9246 AD9271 AD9480
AD9211_250 AD9218_40_1V AD9229_65 AD9237_40 AD9245_65 AD9254 AD9268_105 AD9444 AD9461_130_3p4V AD9627 AD6655 AD9228 AD9248 AD9272 AD9600
AD9211_300 AD9218_65_2V AD9230_170 AD9237_65 AD9245_80 AD9255_105 AD9268_125 AD9445_105_2V AD9480 AD9629_20 AD6657 AD9229 AD9251 AD9273 AD9601

30. What is the Future for ADIsimADC?
 Support for high-precision ADCs <20 MSPS
 16-bit
to 24-bit delta sigmas and PULSARs
 Depends on proxies we identify are important
 Support for more accurate models
 Better integration with SPI control software
 User defined phase noise profiles
 Arbitrarily oversampled inputs
 Statistical distribution of products (Monte Carlo)
 Temperature sensitivities
 Open to suggestions!

31. What is the Future of Behavioral Modeling?
 Support for precision ADCs
 Support for DACs
 Support for clocks
 Support for amplifiers
 Support for modulators/demodulators
 Need feedback!

32. Outline
 Modeling Overview
 Who am I?
 What is Converter Simulation?
 Why Model at All?
 How Does One Model Behavior?
 How Does One Model Converter Behavior?
 Modeling Converter Behavior
 Can behavioral modeling be any good?
 What can converter modeling do for me?
 Does Analog Devices currently have a converter modeling tool?
 What is the Future for Behavioral Modeling?
 Review
 Q&A
32

33. Review
 Behavioral modeling has been shown to be a viable and effective technology
 Purposes
 Live datasheet
 Didactic
 Product selection
 Product evaluation
 System level simulation
 Analog Devices freely offers ADIsimADC, a converter behavioral modeling tool
as part of its “whole product” initiative
 We want this tool to be part of a dialog between you and us
 Give us feedback
 Provide suggestions
 Try and break it
 Analog Devices is committed to maturing this technology
33

34. Next webcast
 RF Detectors
 February 16th at Noon (ET)
 Challenges in Embedded Design for real-time systems
 March 16th at Noon (ET)
www.analog.com/webcast
34

35. Fundamentals Webcasts 2011
 January Introduction and Fundamentals of Sensors
 February The Op Amp
 March Beyond the Op Amp
 April Converters, Part 1, Understanding Sampled Data Systems
 May Converters, Part 2, Digital-to-Analog Converters
 June Converters, Part 3, Analog-to-Digital Converters
 July Powering your circuit
 August RF: Making your circuit mobile
 September Fundamentals of DSP/Embedded System design
 October Challenges in Industrial Design
 November Tips and Tricks for laying out your PC board
 December Final Exam, Ask Analog Devices
www.analog.com/webcast

36. Outline
 Modeling Overview
 Who am I?
 What is Converter Simulation?
 Why Model at All?
 How Does One Model Behavior?
 How Does One Model Converter Behavior?
 Modeling Converter Behavior
 Can behavioral modeling be any good?
 What can converter modeling do for me?
 Does Analog Devices currently have a converter modeling tool?
 What is the Future for Behavioral Modeling?
 Review
 Q&A
36

37. The World Leader in High Performance Signal Processing Solutions
Thank You!