Differential Signal Timing Compensation for Skew-Free Testing

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Solution Overview

Problem

In test apparatuses using differential signal transmission, skew between positive and negative signals due to length differences in transmission lines leads to operational errors in semiconductor device testing, making accurate signal measurement difficult.

Innovation Solution

A differential signal transmission apparatus with a delay compensating circuit that adjusts the transmission time difference between positive and negative signals using variable compensation time, ensuring synchronized signal transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If independent coaxial cables are used for positive and negative signal transmission, then signal transmission capability is improved, but skew between signals occurs due to length differences

Engineering Contradiction:

Improvesignal transmission capabilityVSAvoidsignal skew

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The patent combines the positive and negative signal transmission into a single coaxial cable using a splitter, ensuring both signals travel through the same transmission medium and arrive simultaneously, thereby eliminating skew while maintaining transmission capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

A splitter is introduced as an intermediary device that divides the differential signal into positive and negative components within the same coaxial cable, ensuring equal path length and simultaneous arrival at the device under test

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If transmission line length differences exist, then routing flexibility is improved, but skew between positive and negative signals occurs

Engineering Contradiction:

Improverouting flexibilityVSAvoidsignal measurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

By merging both signal paths into a single coaxial cable transmission, the patent eliminates length differences while maintaining routing flexibility through the splitter configuration, ensuring accurate signal measurement

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If separate transmission lines are used for each signal, then signal independence is improved, but time difference between signals occurs

Engineering Contradiction:

Improvesignal transmission independenceVSAvoidtime difference between signals

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The splitter acts as an intermediary that maintains signal independence through separate output channels while ensuring both signals traverse the same transmission path length, eliminating time differences

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20100001776A1Differential signal transmitting apparatus and a test apparatus

Publication Date: 2010.01.07 ADVANTEST CORP

AI summary

Provided is a differential signal transmission apparatus that transmits a differential signal expressed by a potential difference between a positive signal and a negative signal, including a positive signal transmission line that transmits the positive signal; a negative signal transmission line that transmits the negative signal; and a delay compensating circuit that compensates for a time difference between the positive signal and the negative signal with a variable compensation time.