Programmable DFE Tap Control for Faster Equalization Convergence
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Solution Overview
Problem
Decision feedback equalizers (DFEs) face challenges in equalizing frequency responses of received signals due to prolonged reflections of previously received signals, which complicates the process of increasing eye opening without amplifying noise.
Innovation Solution
The implementation of a DFE with programmable taps and a Sign Sign Least Mean Square (SSLMS) algorithm for updating tap weights, where tap outputs are selectively enabled based on threshold comparisons of impulse responses, allowing for adaptive adjustment of tap weights and bias factors to optimize signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a DFE equalizes frequency response of signals with prolonged reflections, then eye opening increases, but noise amplification occurs
Solution Approach 1:
The patent changes the parameter of tap weight values dynamically based on impulse response characteristics. By adjusting tap weights according to the measured impulse response and selectively enabling/disabling taps based on threshold comparisons, the system adapts to different channel conditions, improving eye opening while controlling noise amplification through parameter optimization
Solution Approach 2:
The patent implements dynamic adaptation by continuously updating tap weights using the SSLMS algorithm based on observed impulse responses. The system transitions from static to dynamic equalization, where tap weights and enable states are adjusted in real-time to match changing channel conditions, resolving the contradiction between eye opening improvement and noise control
2Measurement precision
If tap weights are updated continuously to handle varying impulse responses, then equalization accuracy improves, but convergence speed decreases
Solution Approach 1:
The patent applies partial action by selectively enabling only those taps whose weights exceed a predetermined threshold. Instead of continuously updating all tap weights, the system updates only the necessary subset of taps, reducing computational overhead and convergence time while maintaining equalization accuracy for the most significant taps
Solution Approach 2:
The system changes the operational parameter by switching between different tap configurations based on impulse response characteristics. By adjusting which taps are active and their corresponding weights dynamically, the system achieves fast convergence to accurate equalization without requiring continuous full-system updates
3Reliability
If all tap outputs are always enabled to handle complex impulse responses, then equalization performance improves, but power consumption increases
Solution Approach 1:
The patent applies local quality by enabling different tap outputs for different input signal conditions. Instead of uniformly enabling all taps, the system selectively activates only those taps necessary for the current impulse response characteristics, optimizing power consumption locally for each operational condition while maintaining equalization performance
Solution Approach 2:
The system dynamically adjusts the number of active taps based on the measured impulse response. By transitioning between different tap configurations, the system optimizes power consumption in real-time, enabling more taps when performance is needed and fewer taps when power efficiency is prioritized, resolving the contradiction between reliability and energy use
Data Source
AI summary
A Decision Feedback Equalizer (DFE) with programmable taps includes a summer configured to receive a DFE input signal. Delay elements are coupled to the summer. The delay elements are connected in series. Each delay element provides a respective delayed signal of an input signal to the delay element. A weight generator is configured to provide tap weights. The DFE is configured to multiply each tap weight to the respective delayed signal from the respective delay element to provide tap outputs. Each tap output is selectively enabled to be added to the summer or disabled based on a first comparison of a first threshold value and each impulse response or each tap weight corresponding to the respective tap output, where the impulse response is the DFE input signal in response to a pulse signal transmitted through a channel.