Phase Mixer Compensation in CDR for Nonlinear Clock Alignment
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Solution Overview
Problem
Clock and data recovery (CDR) circuitry experiences differential non-linearity due to phase mixer (PMIX) circuitry, leading to errors in data signal alignment and performance degradation in communication systems.
Innovation Solution
Incorporation of compensation circuitry and phase accumulation circuitry that generates a compensation signal based on a compensation value to mitigate non-linearity within the PMIX circuitry, improving the alignment of clock signals and reducing errors in data reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase mixer circuitry is used in CDR circuitry, then clock signal generation is enabled, but differential non-linearity occurs leading to data alignment errors
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values in a lookup table that counteract the differential non-linearity of the phase mixer. These compensation values are applied before the phase mixing operation to pre-correct the phase errors, thereby improving data alignment accuracy without requiring changes to the physical phase mixer structure
Solution Approach 2:
The patent implements feedback by continuously monitoring the phase alignment errors and using this information to adjust the compensation values applied to the phase mixer input. The system measures the actual phase differences and feeds this information back to the compensation circuitry, which then adjusts the lookup table values or applies real-time corrections to maintain accurate data alignment
2Productivity
If phase mixer circuitry operates without compensation, then circuit simplicity is maintained, but non-linearity causes performance degradation
Solution Approach 1:
The patent introduces an intermediary compensation circuit between the phase accumulator and the phase mixer. This intermediary layer processes the phase accumulator output through a lookup table or compensation function that corrects the non-linearity before it reaches the phase mixer, thereby improving data reception quality without fundamentally changing the phase mixer itself
Solution Approach 2:
The compensation values are pre-calculated and stored in a lookup table during manufacturing or system initialization. This preliminary action allows the system to apply corrections without real-time computation complexity, maintaining relatively simple operational circuitry while achieving improved performance
Data Source
AI summary
A system and method which compensates for phase mixer circuit non-linearities within a clock and data recovery (CDR) system during active operation. The CDR system includes compensation circuitry and phase accumulation circuitry. The compensation circuitry generates a first compensation signal based on a first compensation value. The phase accumulation circuitry receives the first compensation signal and a phase accumulator input update signal. The phase accumulation circuitry combines the first compensation signal with the phase accumulator input update signal to compensate for a first non-linearity within phase mixer (PMI) circuitry.