Error-Gated CDR Control for Faster Recovery After Signal Noise
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Solution Overview
Problem
Conventional clock data recovery systems require a long time to recover original data and clock after temporary noise superimposition on digital signals, especially due to external factors like static electricity, leading to frequency and phase mismatches.
Innovation Solution
The reception apparatus incorporates an error detection unit to quickly identify signal errors, allowing for processes such as stopping phase/frequency comparison, halting equalizer control operations, or instructing the transmission of training patterns to rapidly re-establish synchronization and compensate for waveform changes, thereby reducing recovery time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is used to recover clock and data from digital signal, then clock and data recovery is achieved, but recovery time is excessively long after noise superimposition stops
Solution Approach 1:
The error detection unit performs preliminary detection of signal errors before the feedback control mechanism can respond. When noise is superimposed on the digital signal, the error detection unit immediately identifies the error condition, allowing the system to take preliminary corrective actions (such as pausing feedback control or switching to alternative recovery paths) before the full feedback loop can react, thereby significantly reducing the recovery time after noise stops.
Solution Approach 2:
The system implements a dual feedback mechanism: the original feedback control for clock and data recovery, and a new feedback loop through the error detection unit that monitors signal quality and triggers appropriate responses. This additional feedback path allows the system to detect errors and adjust its behavior in real-time, preventing prolonged recovery periods by immediately responding to noise conditions and facilitating faster return to normal operation once noise stops.
2Reliability
If feedback control operates continuously on digital signal, then clock frequency/phase and data value recovery is maintained, but error propagation occurs when noise is superimposed
Solution Approach 1:
The error detection unit acts as an intermediary between the noisy digital signal and the feedback control mechanism. It monitors the signal for errors and intervenes by triggering appropriate responses (such as pausing feedback control or alerting higher-level control systems) before errors can propagate through the feedback loop. This intermediary function protects the continuous recovery capability from being compromised by noise-induced error propagation.
3Device complexity
If conventional CDR technology is used, then system simplicity is maintained, but transmission efficiency deteriorates due to long recovery time
Solution Approach 1:
The CDR system is segmented into distinct functional units: the original feedback control mechanism for clock and data recovery, and a separate error detection unit that independently monitors signal quality. This segmentation allows the error detection unit to operate in parallel without interfering with the core recovery function, adding error detection capability while maintaining relative system simplicity and enabling faster response to noise conditions to improve transmission efficiency.
Data Source
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AI summary
Provided is a reception apparatus capable of shortening a time period until the original data and clock can be recovered from a digital signal after temporary superimposition of noise on the digital signal stops. A reception apparatus 20 includes a receiver unit 21, a voltage-controlled oscillator 22, a sampler unit 23, a control voltage generation unit 24, an error detection unit 25, a training control unit 26, and an equalizer control unit 27. The receiver unit 21 includes an equalizer unit 21 A. When the error detection unit 25 detects an error of a digital signal, the reception apparatus 20 causes a phase/frequency comparison by the control voltage generation unit 24 to be stopped.