Transmitter De-emphasis and Receiver Equalization for Data Link BER

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Solution Overview

Problem

High speed data links face a trade-off between link length and bit error rate (BER), as the BER increases with link length and data rate due to frequency distortion and inter-symbol interference in transmission lines.

Innovation Solution

Incorporating a transmitter de-emphasis circuit to pre-distort input signals and a passive receiver equalization circuit to compensate for frequency distortion, flattening the amplitude response and reducing BER.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the length of the data link is increased, then the transmission distance is improved, but the bit error rate increases due to frequency distortion and inter-symbol interference

Engineering Contradiction:

Improvedata link lengthVSAvoidbit error rate

Core Design Contradiction:

Length of stationary objectVSReliability

Solution Approach 1:

The transmitter de-emphasis circuit applies preliminary anti-action by pre-distorting the transmitted signal to anticipate and counteract the frequency distortion that will occur during transmission. This pre-compensation approach reduces the impact of transmission line effects before the signal deteriorates, allowing longer link lengths while maintaining acceptable bit error rates

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The receiver equalization circuit applies preliminary action by processing the received signal to pre-flatten its amplitude response before final detection. This preliminary correction of frequency distortion at the receiver end further compensates for transmission line effects, enabling extended data link lengths without excessive bit error rate degradation

Inventive Principle:

Principle #10Preliminary action

2Speed

If the data rate is increased, then the transmission speed is improved, but the bit error rate increases due to frequency distortion and inter-symbol interference

Engineering Contradiction:

Improvedata rateVSAvoidbit error rate

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The transmitter de-emphasis circuit applies preliminary anti-action by pre-distorting the transmitted signal to anticipate and counteract the frequency distortion that will occur during high-speed transmission. This pre-compensation approach reduces the impact of transmission line effects before the signal deteriorates, allowing higher data rates while maintaining acceptable bit error rates

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The receiver equalization circuit applies preliminary action by processing the received signal to pre-flatten its amplitude response before final detection. This preliminary correction of frequency distortion at the receiver end further compensates for transmission line effects, enabling higher data rates without excessive bit error rate degradation

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7586987B2High speed data link with transmitter equalization and receiver equalization

Publication Date: 2009.09.08 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

A high speed data link includes transmitter equalization and (passive) receiver equalization to compensate for frequency distortion of the data link. In one embodiment, the transmitter equalization is performed with a de-emphasis circuit. The transmitter de-emphasis circuit pre-distorts an input signal to compensate for at least some of the frequency distortion in the data caused by the transmission line. The (passive) receive equalization circuit further compensates for the frequency distortion at the output of the transmission line to flatten the amplitude response of the output signal, and thereby reduce inter-symbol interference, improve media reach and improve the bit error rate (BER).