Clock and Data Recovery Circuit for Attenuated Signal Transition Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing clock and data recovery (CDR) circuits in communication systems face inefficiencies when dealing with highly attenuated multi-level data signals and varying communication channel loss profiles, often requiring prior knowledge of amplitude levels and struggling with accurate transition detection due to inter-symbol interference (ISI).
Innovation Solution
A CDR circuit comprising a clock-recovery circuit, phase-recovery circuit, analog-to-digital converter, and data-recovery circuit that generates a clock signal and accurately detects amplitude levels without prior knowledge of amplitude levels, operating effectively across different communication channel loss profiles by optimizing phase and frequency synchronization and sampling positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing CDR circuits are used to detect transitions in highly attenuated multi-level data signals, then the circuit structure is simple, but the transition detection accuracy deteriorates due to inter-symbol interference causing amplitude level overlap
Solution Approach 1:
The patent applies preliminary action by performing equalization processing on the received signal before transition detection. The equalizer compensates for inter-symbol interference effects in advance, restoring the amplitude levels of the multi-level signal so that transitions can be accurately detected despite channel attenuation and ISI conditions.
Solution Approach 2:
The patent introduces an intermediary equalizer between the receiver front-end and the transition detector. This equalizer acts as a mediator that compensates for channel distortion and ISI, providing a cleaned-up signal to the transition detection circuit, thereby improving detection accuracy without requiring fundamental changes to the detector itself.
2Adaptability or versatility
If CDR circuits require prior knowledge of amplitude levels to operate, then the detection algorithm is simple, but the adaptability to different communication channels deteriorates
Solution Approach 1:
The patent applies self-service by implementing automatic amplitude level estimation within the CDR circuit. Instead of requiring external provision of amplitude level information, the circuit autonomously estimates the amplitude levels from the received signal through training sequences or statistical analysis, enabling it to adapt to different channels independently.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the equalizer coefficients and detection thresholds based on the estimated channel characteristics and signal conditions. This allows the CDR circuit to adapt its operation to different communication channels with varying loss profiles without requiring manual reconfiguration.
3Duration of action of moving object
If CDR circuits operate with attenuated signals through long-distance transmission, then the transmission distance is extended, but the signal quality deteriorates due to high attenuation and noise
Solution Approach 1:
The patent applies preliminary action by implementing equalization and clock recovery before data detection. This preliminary processing compensates for attenuation and synchronization issues that accumulate over long transmission distances, restoring signal quality before the critical data sampling operation occurs.
Solution Approach 2:
The patent implements feedback mechanisms where the detected data is used to refine the equalizer coefficients and clock phase estimates. This feedback loop continuously improves signal quality compensation, allowing the system to maintain reliability even after long-distance transmission through iterative optimization.
Data Source
AI summary
A clock and data recovery (CDR) circuit receives a data signal and generates a clock signal and a recovered data signal. The CDR circuit includes a clock-recovery circuit (CRC), a sampling phase-recovery circuit (PRC), an analog-to-digital converter (ADC), and a data-recovery circuit (DRC). The CRC receives the data signal and generates an intermediate clock signal. The PRC receives the intermediate clock signal, a sampled data signal and the recovered data signal, and generates the clock signal. The ADC receives the data signal and generates the sampled data signal. The DRC receives the sampled data signal and generates the recovered data signal. The clock signal is phase and frequency synchronized with the data signal.