Sampling Phase Interpolator Feedback for Clock Phase Linearity
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Solution Overview
Problem
Phase interpolators in CDR circuits suffer from non-linearity and integral nonlinearity mismatch due to semiconductor manufacturing variations, affecting the quality of generated data.
Innovation Solution
A phase interpolator design comprising a phase detector, filter, and oscillator that adjusts clock signal phases using a detection result to mitigate variations, employing a sampling rotational phase detector and a voltage- or current-controlled oscillator to generate accurate phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a typical PI-based CDR is used, then high integration and low power consumption are achieved, but non-linearity between control codes and clock phase affects data quality
Solution Approach 1:
The patent implements a feedback mechanism where the phase detector detects the phase difference between the input clock signal and the generated clock signal, and the feedback controller adjusts the control codes based on this detection to compensate for non-linearity. This closed-loop feedback system continuously corrects phase accuracy while maintaining the integrated PI-based CDR structure.
Solution Approach 2:
The patent dynamically adjusts the control codes (electrical parameters) of the phase interpolator based on feedback from the phase detector. By changing these control parameters adaptively, the system compensates for the inherent non-linearity and achieves accurate phase generation without requiring a complete redesign of the integrated structure.
2Adaptability or versatility
If multiple phase interpolators are used, then phase coverage is improved, but integral nonlinearity mismatch due to manufacturing variations worsens
Solution Approach 1:
The patent applies local quality by individually calibrating and adjusting each phase interpolator's control codes based on its specific manufacturing variations. The feedback mechanism allows each interpolator to be optimized locally, compensating for its unique non-linearity characteristics while maintaining overall phase coverage across multiple interpolators.
Solution Approach 2:
The system dynamically adjusts the control parameters of each phase interpolator based on real-time feedback, allowing each device to operate at its optimal performance point despite manufacturing variations. This parameter adaptation enables multiple interpolators to work together with reduced nonlinearity mismatch.
3Measurement precision
If phase interpolator control codes are adjusted, then phase accuracy is improved, but non-linearity in the control code to phase relationship increases
Solution Approach 1:
The patent uses feedback from the phase detector to continuously monitor the actual phase output and adjust the control codes accordingly. This feedback loop compensates for the non-linear relationship between control codes and phase, maintaining accurate phase generation despite the inherent non-linearity in the control mechanism.
Solution Approach 2:
The system transitions from static control codes to dynamic adjustment of control parameters based on real-time phase detection. This dynamic approach allows the control codes to adapt to the non-linear characteristics, optimizing phase accuracy across different operating conditions rather than relying on fixed linear relationships.
Data Source
AI summary
The present invention provides phase interpolator including a phase detector, a filter and an oscillator is disclosed. The phase detector is configured to receive a first clock signal and a second clock signal, and sample the first clock signal and the second clock signal to generate a detection result, wherein phases of the first clock signal and the second clock signal are different. The filter is configured to filter the detection result to generate a filtered detection result. The oscillator is configured to control frequencies of the first clock signal and the second clock signal, or control a frequency of a sampling clock signal of the phase interpolator according to the filtered detection result.