Replica CDR Path for Mueller-Muller Phase Detector Calibration
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Solution Overview
Problem
Conventional Mueller-Muller phase detectors misalign the main cursor when the impulse response of a transmission line is not symmetric, leading to suboptimal bit error rate performance.
Innovation Solution
A replica clock and data recovery path is introduced to experimentally adjust the phase detector offset and gain without affecting the main CDR path, allowing for improved bit error rate by determining optimal settings for the phase detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional Mueller-Muller phase detector is used in the main CDR path, then data reception is continuous, but gain and offset errors cause misalignment and suboptimal bit error rate performance
Solution Approach 1:
The system is divided into two separate CDR paths: a main CDR path for continuous data reception and a replica CDR path for calibration. The replica path is a segmented copy of the main path that allows independent adjustment of phase detector parameters without affecting the main data flow, thereby resolving the contradiction between maintaining continuous operation and achieving precise alignment.
Solution Approach 2:
A replica CDR path is created as a copy of the main CDR path. This replica includes a replica phase detector with adjustable gain and offset parameters. By copying the main path structure and using it for calibration purposes, the system can optimize phase detector settings without disrupting the main data reception, thus improving bit error rate performance while maintaining measurement precision.
2Measurement precision
If phase detector offset and gain are adjusted in the main CDR path, then alignment accuracy improves, but data reception is disrupted
Solution Approach 1:
The CDR system is segmented into two independent paths: the main CDR path that maintains continuous data reception and the replica CDR path that handles calibration operations. This segmentation allows phase detector parameters to be adjusted in the replica path without disrupting the main data flow, simultaneously achieving alignment accuracy and maintaining productivity.
Solution Approach 2:
The replica CDR path acts as an intermediary for calibration operations. Instead of directly adjusting the main phase detector (which would disrupt data reception), the adjustment is performed on the replica phase detector, and the optimized parameters are then transferred to the main phase detector. This intermediary approach enables precision improvement without productivity loss.
3Reliability
If a replica CDR path is added for calibration, then phase detector settings can be optimized without disrupting main path, but device complexity increases
Solution Approach 1:
The replica CDR path is created by copying the essential components of the main CDR path, including a replica phase detector, replica equalizer, and replica slicer. This copying approach allows the system to optimize phase detector settings in the replica path and transfer the learned parameters to the main path, improving reliability while managing complexity through parameter sharing and structural similarity.
Solution Approach 2:
The replica phase detector includes adjustable gain and offset parameters that can be modified during calibration. By changing these parameters in the replica path and observing the effect on calibration metrics, the system can optimize performance without permanently altering the main path configuration. This parameter adjustability enables reliability improvement while keeping the base architecture relatively simple.
Data Source
AI summary
Apparatus and methods reduce channel-dependent phase detector offset and/or gain errors. A conventional Mueller-Muller phase detector places a main cursor at the midpoint of a pre-cursor and a post-cursor. However, for example, when the impulse response of an associated transmission line is not symmetric, the main cursor can be misaligned by conventional Mueller-Muller techniques. By providing a replica clock and data recovery path, trial and error experiments on the phase detector offset and/or gain can be performed, and relatively good values found for the phase detector offset and/or gain without disturbing the reception of data by the phase detector that is being used to receive data. These settings can then be used by the phase detector that is being used to receive data, which can improve the bit error rate of the phase detector.