Decision Feedback Equalizer Timing for Stable Tap2 ISI Correction
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Solution Overview
Problem
In high-speed data transmission, the output of the tap2 path in decision feedback equalizers often fails to reach a stable value due to timing constraints, leading to poor Inter-Symbol Interference (ISI) elimination effectiveness.
Innovation Solution
A decision feedback equalizer circuit is designed with a first and second adder circuit, sampler amplifiers, and a correction parameter processing element, where the time sequence of the second clock signal is prior to the first clock signal, ensuring the target correction data is stable and accurate for ISI elimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple tap paths are used to eliminate ISI influence, then the ability to correct inter-symbol interference is improved, but the timing constraint causes the tap2 path output to fail reaching stable value
Solution Approach 1:
The patent introduces a preliminary sampling stage using a first sampler amplifier to capture the tap2 path output before the main decision feedback equalization process. This preliminary action allows the system to obtain a stable reference value early in the signal processing chain, before timing constraints prevent stability in subsequent stages. The sampled value is then used in the feedback correction process, effectively decoupling the stability requirement from the timing-constrained tap2 path.
Solution Approach 2:
The patent introduces an intermediate sampling and holding mechanism between the tap2 path and the final correction process. The first sampler amplifier acts as an intermediary that captures and holds the tap2 path output at a specific moment, providing a stable intermediate value that can be used for correction without requiring the original tap2 path to remain stable throughout the entire processing cycle. This intermediary stage bridges the gap between the unstable tap2 output and the stable correction requirement.
2Measurement precision
If the tap2 path is used for correction, then the correction capability is improved, but the load and capacitance prevent the path from recovering to stable potential during sampling
Solution Approach 1:
The system performs preliminary sampling of the tap2 path output using the first sampler amplifier before the main correction process. This preliminary action captures the correction value at an optimal moment when the tap2 path has sufficient time to recover, avoiding the need for the path to remain stable during the entire correction cycle. The sampled value is then held and used for correction, eliminating the time loss issue.
Solution Approach 2:
The patent introduces dynamic timing control where the sampling moment of the first sampler amplifier is specifically positioned to allow adequate recovery time for the tap2 path. The system dynamically adjusts the sampling timing to occur after the tap2 path has recovered from previous corrections but before the next correction cycle begins, optimizing both accuracy and recovery time utilization.
Data Source
AI summary
The present disclosure provides a decision feedback equalizer circuit. The decision feedback equalizer circuit includes: a first adder circuit, configured to add sampled data, first correction data and target correction data; a first sampler amplifier, configured to sample data output by the first adder circuit through a first signal component in a first clock signal to obtain a first sampling result; a second adder circuit, configured to add the sampled data, the first correction data and the target correction data; a second sampler amplifier, configured to sample data output by the second adder circuit through a second signal component in the first clock signal to obtain a second sampling result; and a correction parameter processing element, configured to determine the target correction data through a second clock signal, the first sampling result and the second sampling result.