Programmable HDMI Cable Equalization for Skew Compensation

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Solution Overview

Problem

High-speed differential signaling cables, such as those used for HDMI, suffer from bandwidth limitations and differential skew, leading to signal distortion and attenuation, which existing solutions like passive equalizers cannot adequately address due to random variations in cable characteristics and power constraints.

Innovation Solution

A programmable HDMI cable with an embedded boost device featuring an equalizer circuit and deskew circuit, powered solely by the cable's signals, which adjusts frequency response and compensates for differential skew using adjustable parameters stored in a parameter memory.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the cable length is increased to extend transmission distance, then the coverage area is improved, but the signal attenuation and bandwidth limitation worsen due to the low-pass filter effect

Engineering Contradiction:

Improvecable lengthVSAvoidsignal quality

Core Design Contradiction:

Length of stationary objectVSReliability

Solution Approach 1:

An active boost device is introduced as an intermediary component within the cable structure. This boost device receives the attenuated signal from the cable, amplifies it using an amplifier circuit, and retransmits the restored signal to the receiver, thereby compensating for the signal degradation caused by long cable transmission

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The boost device dynamically adjusts signal parameters including amplitude amplification through variable gain amplifiers, frequency response modification through equalizer circuits with adjustable coefficients, and timing alignment through programmable delay elements. These parameter changes compensate for cable-induced signal degradation

Inventive Principle:

Principle #35Parameter changes

2Reliability

If passive equalizer circuits are used to compensate for signal attenuation, then the bandwidth limitation is partially addressed, but the solution is inadequate due to random variations in cable characteristics and power constraints

Engineering Contradiction:

Improvesignal compensationVSAvoidcable characteristic variation

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system transitions from static passive equalization to dynamic active equalization. The boost device incorporates programmable equalizer circuits with adjustable coefficients, variable gain amplifiers, and controllable delay elements that can be dynamically tuned to match the specific characteristics of different cable instances, enabling adaptation to random variations in cable properties

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements feedback mechanisms where the boost device receives control signals from the receiver end indicating signal quality metrics. Based on this feedback, the boost device adjusts its amplification gain, equalizer coefficients, and delay settings to optimize signal compensation for the specific cable being used

Inventive Principle:

Principle #23Feedback

3Reliability

If external power sources are used to power active signal boosting devices, then the signal quality improvement is achieved, but the system complexity and power requirements increase

Engineering Contradiction:

Improvesignal boostingVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The boost device is designed to be self-powered by harvesting energy directly from the differential signal pairs it processes. The device uses the signal power available on the cable to operate its amplifier and control circuits, eliminating the need for separate external power sources while maintaining signal boosting functionality

Inventive Principle:

Principle #25Self-service

4Ease of manufacture

If the cable bandwidth is limited acting as a low-pass filter, then the manufacturing simplicity is maintained, but the high-frequency signal attenuation and edge sharpness degradation worsen

Engineering Contradiction:

Improvecable constructionVSAvoidsignal edge sharpness

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The system replaces the passive mechanical/electrical low-pass filter characteristic of the cable with an active electronic signal processing system. The boost device uses electronic amplifiers, equalizer circuits, and digital signal processing to restore high-frequency components and sharpen signal edges that were attenuated by the cable's inherent low-pass filtering

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS7936197B2Programmable high-speed cable with boost device

Publication Date: 2011.05.03 PARADE TECHNOLOGIES LTD

AI summary

An HDMI cable carries high speed encoded data which are transmitted differentially over data channels, along with a clock. High-frequency loss and differential skew within a differential signal may be compensated by analog circuits embedded in the cable. These embedded circuits are tuned at production for best performance by observing the quality of the recovered analog signal. The embedded circuits are powered by a combination of power sources, both carried within the cable, and harvested from the high-speed signals themselves.