1© 2009 Agilent Technologies, Inc.

July 29th, 2009

Signal Integrity Design Using

Fast Channel Simulator and

Eye Diagram StatisticsSanjeev Gupta,Signal Integrity Applications Expert

Colin Warwick,Signal Integrity Product Manager

Agilent EEsof EDA

July 29th, 2009

Channel

∑

Jitter

EQ

RX

ReceivedSignal

∑

JitterXTalk1

PRBS EQ

∑

JitterXTalkN

PRBS EQ

∑

JitterTX

PRBS EQ

2© 2009 Agilent Technologies, Inc.

July 29th, 2009

Agenda

• Challenges associated with serial link analysis

• Introduction to Channel Simulator:

– Bit-by-bit mode

– Statistical mode

• Demo

• Comparison with measured data and with StatEye

• Summary and further resources

• Complete the feedback survey to enter the prize drawing

• Q&A

3© 2009 Agilent Technologies, Inc.

July 29th, 2009

Introduction to Serial Link

Channel

∑

Jitter

EQ

RX

ReceivedSignal

∑

JitterXTalk1

PRBS EQ

∑

JitterXTalkN

PRBS EQ

∑

JitterTX

PRBS EQ

4© 2009 Agilent Technologies, Inc.

July 29th, 2009

Challenges and Solutions with Serial Link Analysis

Challenges

• Low BER performance (10−12 or less)used to imply long simulations

• Issues with interconnect models

• Multiple crosstalk channels

• Jitter modeling for transmitter and receiver

Solution: ADS Channel Simulator

• New in ADS 2009: Bit-by-bit mode

• New in ADS 2009 Update 1: Statistical mode

5© 2009 Agilent Technologies, Inc.

July 29th, 2009

Comparison of Techniques in ADS 2009 Update 1

Arbitrarily low~10-6~10-3BER floor in one

minute simulation

LTI, fixed (general) bit pattern, fixed eq. taps

LTI, any specific bit pattern, adaptive eq. taps, IBIS AMI

Linear and non-linear circuits

Applicability

Statistical calculations based on step response

Bit-by-bit superposition of step responses

Modified nodal analysis of Kirchoff’s current laws for every time step

Method

Channel

Simulator:

Statistical mode

Channel

Simulator:

Bit-by-bit mode

Transient

Simulator

6© 2009 Agilent Technologies, Inc.

July 29th, 2009

Channel Simulator: Bit-by-bit mode

1) SPICE-like transient response of single bit: runs on existing schematic

2) Response of millions of bits per minute using signal processing techniques

ISI

Superposition

7© 2009 Agilent Technologies, Inc.

July 29th, 2009

Channel Simulator: Statistical mode

1) SPICE-like transient response of single bit: runs on existing schematic

2) Statistical calculations including ISI, crosstalk, jitter specification, equalizers, and encoding

8© 2009 Agilent Technologies, Inc.

July 29th, 2009

Demo

9© 2009 Agilent Technologies, Inc.

July 29th, 2009

StatEyeADS Statistical Mode ADS Bit-by-bit Mode

StatEye

ADS Statistical Simulator

ADS Channel Simulator (1 M bits)

StatEye

ADS Channel Simulator (1 M bits)

ADS Statistical SimulatorTiming

Bathtub

VoltageBathtub

ADS Channel Simulator Versus StatEye

NoYesMultiple X-talks

Simplistic: overestimates eye openingAccurate treatment of RJ, PJ and DCDTX jitter model

StatEyeADS

10© 2009 Agilent Technologies, Inc.

July 29th, 2009

Comparison with Measured Data

Measurements were performed

using Agilent DCA-J 210 bit pattern

from signal generator ADS Channel Simulator, Bit-

bit mode (PRBS 210)

ADS Channel Simulator, Statistical mode (infinitely long bit sequence)

Overlaid plot of Measurement and simulated data for ( 210) bit pattern

11© 2009 Agilent Technologies, Inc.

July 29th, 2009

Comparison with Measured Data

Measured eye diagram with four

tap FFE equalizer

Simulated eye diagram with four tap FFE equalizer using statistical

simulatorComparison of measured and

simulated data

Tyco Backplane

12© 2009 Agilent Technologies, Inc.

July 29th, 2009

Benefits of ADS Channel Simulator

• One button selection of bit-by-bit or statistical mode

• Accurate simulation of frequency domain models

– Enforces passivity and causality on simulated and measured S-parameters

• Allows arbitrary channel and crosstalk topology: schematic and layout

– Perform crosstalk analysis for arbitrary number of aggressor channels

• Requires only short simulation length: pulse response of channels ~10s of bits

– Produces reliable eye diagram and BER plots within seconds

• FFE/DFE tap optimization

– Automatically open a closed eye

• Accurately model all jitter components (Rj, PJ, DCD) for TX/RX

• Provide worst case eye diagram performance at a given BER

• Eye probes are compatible with Agilent’s oscilloscope mask file

• Automatic optimization of eye diagram and BER

– Batch mode simulation supported for all measurement goals

13© 2009 Agilent Technologies, Inc.

July 29th, 2009

Prize Drawing

Registrants* who completely fill out the feedback form by October 29, 2009 will be entering into a drawing for:

• One of two $75 Amazon.com gift certificates

• One of twenty tickets (each a $648 value) for our new, intensive one-day hands-on class on ADS Channel Simulator

– Winner choose either face-to-face in Santa Clara, CA or live, interactive, instructor-led, web-based version

*Drawing only open to residents of the 50 United States and Canada (except Quebec)

14© 2009 Agilent Technologies, Inc.

July 29th, 2009

Summary and Next Steps

Summary

• Explore a large design space quickly using statistical channel simulation and optimization of BER contours versus eye mask goals

Next steps

• Evaluate ADS 2009, shipping now

– Application page:http://www.agilent.com/find/signal-integrity

• ADS 2009 Update 1http://www.agilent.com/find/eesof-ads2009-update1

– Product Shipment in 2009H2