Adaptive CDR Loop Control for Variable Jitter Tolerance
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Solution Overview
Problem
Conventional CDR circuits in high-speed serial input/output devices face challenges in effectively managing jitter signals from various sources, leading to bit-error rates higher than specifications due to fixed parameter settings that are not adaptable to different jitter frequencies and amplitudes.
Innovation Solution
An adaptive CDR loop dynamic control circuit that senses jitter frequencies and amplitudes, dynamically updating parameters such as first and second-order loop gains to optimize clock signal generation, thereby improving jitter tolerance and reducing bit-error rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed parameter settings are used in CDR circuits, then device complexity is reduced, but jitter tolerance degrades and bit-error rates increase
Solution Approach 1:
The patent implements dynamic parameter adjustment in the CDR circuit by introducing an adaptive control mechanism that continuously monitors jitter characteristics and modifies loop filter parameters (Kp, Ki) in real-time. This transforms the previously static parameter configuration into a dynamic system that adapts to varying jitter conditions, thereby improving jitter tolerance without requiring overly complex fixed-parameter designs.
Solution Approach 2:
The patent changes the parameters of the CDR circuit based on detected jitter frequency and amplitude. Specifically, it adjusts the proportional gain (Kp) and integral gain (Ki) of the loop filter according to the measured jitter characteristics. This parameter adaptation allows the circuit to optimize its performance for different jitter scenarios, resolving the contradiction between fixed simplicity and adaptive reliability.
2Ease of operation
If fixed parameter settings are used in CDR circuits, then ease of operation is improved, but bit-error rates exceed specifications
Solution Approach 1:
The patent implements a self-adjusting mechanism where the CDR circuit automatically detects jitter characteristics and modifies its own parameters without external intervention. The adaptive control circuit monitors the data signal for jitter, determines appropriate parameter values, and updates the loop filter coefficients autonomously. This self-service capability maintains ease of operation while ensuring bit-error rates meet specifications through continuous optimization.
Solution Approach 2:
The patent introduces a feedback loop that continuously monitors the output of the CDR circuit and uses this information to adjust parameters. The system measures jitter in the recovered clock signal, feeds this information back to the adaptive controller, which then modifies Kp and Ki values to optimize performance. This closed-loop feedback mechanism ensures bit-error rates remain within specifications while maintaining operational simplicity.
3Reliability
If adaptive parameter updating is implemented, then jitter tolerance is improved, but device complexity increases
Solution Approach 1:
The patent segments the CDR circuit into distinct functional blocks: a jitter detection unit that measures jitter characteristics, an adaptive control unit that processes the jitter information, and a parameter adjustment unit that modifies loop filter coefficients. This segmentation allows each component to perform its specific function efficiently, reducing overall system complexity while enabling adaptive parameter updating for improved jitter tolerance.
4Reliability
If dynamic parameter adjustment is used, then bit-error rates are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent implements a conservative parameter adjustment strategy where the adaptive control circuit modifies parameters incrementally rather than making large sudden changes. It uses threshold-based triggering and step-size limitations to ensure that parameter updates remain within safe bounds, reducing the risk of manufacturing variations affecting performance. This partial action approach maintains bit-error rate reduction while relaxing manufacturing precision requirements.
Data Source
AI summary
In accordance with embodiments disclosed herein, there is provided systems and methods for jitter sensing and adaptive control of parameters of clock and data recovery (CDR) circuits. A receiver component includes an adaptive CDR loop dynamic control circuit. The adaptive CDR loop dynamic control circuit is to detect first sinusoidal jitter at a first frequency and a first amplitude and update parameters of the CDR circuit to a first plurality of values based on the first frequency and the first amplitude. The adaptive CDR loop dynamic control circuit is further to detect second sinusoidal jitter at a second frequency and a second amplitude and update the parameters of the CDR circuit to a second plurality of values based on the second frequency and the second amplitude. The first sinusoidal jitter is in a first incoming data signal and the second sinusoidal jitter is in a second incoming data signal.