Multistage Equalizer Filter With Adaptive Gain Against Jitter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multistage equalizer systems struggle to effectively compensate for signal modifications across a wide variety of transmission channels, particularly in terms of jitter performance, due to limitations in estimating and compensating frequency-dependent losses.
Innovation Solution
The proposed equalizer filter employs multiple amplifying compensation stages with monotonically rising gain up to the upper data frequency, allowing for overcompensation up to 30 dB, and incorporates a gain control mechanism with feedback and replica biasing techniques to adjust gain signals, ensuring the signal amplitude remains below saturation levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple adaptive filter stages are arranged with common equalisation control signal, then compensation level is improved, but device complexity increases
Solution Approach 1:
The equalizer is divided into multiple filter stages (first adaptive filter stage, second adaptive filter stage, etc.), each with its own transfer function that is an approximate inverse of a portion of the communications path transfer function. This segmentation allows complex compensation to be distributed across simpler individual stages.
Solution Approach 2:
All adaptive filter stages share a common equalisation control signal that corresponds to the overall communications path transfer function. This universal control mechanism allows a single control system to coordinate multiple filter stages, reducing overall device complexity while maintaining effective compensation.
2Reliability
If multiple tuning signals are used to induce higher frequency gain, then compensation for high frequency losses is improved, but deterministic jitter increases
Solution Approach 1:
The patent applies partial action by limiting the higher frequency gain to a controlled level (e.g., +5 dB to +8 dB per tuning function) rather than applying maximum gain across all frequencies. This partial application of gain reduces deterministic jitter while still providing sufficient compensation for high frequency losses.
Solution Approach 2:
The equalizer employs dynamic gain control where tuning signals are applied adaptively based on the specific communications channel characteristics. The system dynamically adjusts which tuning functions are active and at what gain levels, optimizing the balance between compensation and jitter control for each channel.
Data Source
AI summary
A multistage equalizer filter for compensating a received distorted signal having an amplitude for frequency dependent signal modifications introduced by a transmission channel includes at least one amplifying compensation stage having a gain and a saturation level, the gain being monotonically rising for at least a last decade in frequency below an upper data frequency of the received signal, and a gain control device for controlling the gain of the amplifying compensation stage such that the amplitude of the received signal amplified in the at least one amplifying compensation stage remains below the saturation level of the amplifying compensation stage. The gain may be regulated by separately regulating low frequency gain, mid-frequency gain and higher frequency gain for each of the at least one amplifying compensation stages.