Automated CTLE Selection via Channel Step-Response Waveform

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Solution Overview

Problem

Current methods for CTLE estimation in high-speed transmitter links, such as PCIe, are laborious and prone to over-equalization, making it challenging to accurately identify the optimal CTLE for protocol traffic analysis.

Innovation Solution

An automated method using channel step-response to estimate CTLE, which involves capturing the step-response waveform, generating candidate CTLEs, and selecting the optimal CTLE by analyzing equalized step and frequency responses to avoid over-equalization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If manual CTLE selection is used, then flexibility in protocol traffic analysis is improved, but the process becomes laborious and time-consuming

Engineering Contradiction:

Improveflexibility in protocol traffic analysisVSAvoidtime for manual CTLE selection

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The system automatically selects the optimal CTLE by analyzing the step-response waveform and computing equalized responses, eliminating the need for manual user intervention. The automated process independently performs CTLE selection, equalization application, and protocol traffic analysis without requiring user expertise or time investment.

Inventive Principle:

Principle #25Self-service

2Reliability

If recommended CTLEs are applied to equalize the channel, then channel losses are compensated, but over-equalization may occur interfering with receiver data recovery

Engineering Contradiction:

Improvechannel equalization effectivenessVSAvoidover-equalization interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system computes equalized step-response waveforms and frequency responses for each candidate CTLE, then uses this feedback information to objectively evaluate and select the optimal CTLE. This feedback mechanism prevents over-equalization by comparing actual equalization results against desired performance criteria before final CTLE selection.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary analysis of the step-response waveform and computes equalized responses for all candidate CTLEs before applying any CTLE to the protocol traffic. This preliminary evaluation ensures that the selected CTLE is optimal and will not cause over-equalization, allowing safe application to actual traffic data.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If software CTLE is used for protocol traffic analysis, then flexibility is improved, but a priori knowledge of channel behavior and optimum CTLE is required

Engineering Contradiction:

Improveprotocol traffic analysis flexibilityVSAvoiduser knowledge requirement

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The system automatically captures the step-response waveform, generates candidate CTLEs based on channel characteristics, and selects the optimal CTLE without requiring user input or expertise. The automated process eliminates the need for users to have a priori knowledge of channel behavior or CTLE selection criteria.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system performs preliminary channel characterization by capturing and analyzing the step-response waveform before protocol traffic analysis. This preliminary action automatically extracts channel behavior information and uses it to generate and evaluate candidate CTLEs, eliminating the need for users to provide a priori channel knowledge.

Inventive Principle:

Principle #10Preliminary action

4Speed

If high-speed transmitting devices are tested, then data rate capability is improved, but waveform shape distortion increases making protocol response time identification challenging

Engineering Contradiction:

Improvedata transmission rateVSAvoidprotocol response time identification accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The system applies the selected CTLE to equalize the channel before acquiring protocol traffic data. This preliminary equalization action compensates for channel losses and waveform distortion that occur at high data rates, restoring the waveform shape to enable accurate protocol response time identification.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from step-response analysis to select the optimal CTLE that will compensate for high-speed channel effects. By evaluating equalized responses and selecting the CTLE that best restores waveform shape, the system enables accurate measurement identification despite high data rate distortions.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12339298B2Method of CTLE estimation using channel step-response for transmitter link equalization test

Publication Date: 2025.06.24 TEKTRONIX INC

AI summary

A method of automatically selecting a continuous time linear equalization (CTLE) filter includes capturing a response waveform for a channel of a communication link of a device under test (DUT), generating a set of candidate CTLEs, and automatically selecting the CTLE from the set of candidate CTLEs using the response waveform. A test and measurement instrument has a user interface, a port to allow the instrument to connect to a device under test (DUT), and one or more processors configured to execute code to cause the one or more processors to: generate a set of CTLE candidates; capture a response waveform for the channel; and automatically select the CTLE from the set of candidate CTLEs using the response waveform.