Analog Devices’ Approach to Behavioral Modeling By: Tom MacLeod

1. Farnell & Analog Devices partner to host a webinar on ‘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

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? • It is 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 • It implements 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” • Behavioral Modeling – 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 • Not SPICE (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

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”

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

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

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 • A subset of products (those ending in .PMF) support a register map interface • Example – AD6657

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

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

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” • There is 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…

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. 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. 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

34. Thank You!

35. All materials presented during the webinar will be available on www.element-14.com , on our dedicated group page: In order to support your work and help you develop your designs, you can BUY your “Analog Devices” parts at:www.farnell.com Check our technology website and e-community – element14 for product data, design tools and technology information!