Clock and Data Recovery Loop Gain Adaptation for Jitter Tolerance
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Solution Overview
Problem
Conventional CDR circuits in high-speed serial input/output devices have fixed parameters that are ineffective for varying jitter signals across different frequencies and amplitudes, leading to increased bit-error rates and degraded jitter tolerance due to jitter amplification.
Innovation Solution
An adaptive CDR loop dynamic control circuit that senses jitter frequency and amplitude, dynamically updating first and second-order loop gains to optimize clock signal generation and reduce bit-error rates, thereby improving jitter tolerance and compliance with channel specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed parameters are used in conventional CDR circuits, then device complexity is reduced, but jitter tolerance degrades and bit-error rates increase under varying jitter conditions
Solution Approach 1:
The patent implements dynamic parameter adjustment in the CDR circuit by introducing an adaptive loop filter that modifies its transfer function based on detected jitter frequency. The system transitions from fixed parameters to dynamically adjustable parameters, allowing the CDR circuit to adapt to varying jitter conditions while maintaining manageable complexity through structured adaptation mechanisms.
Solution Approach 2:
The patent changes the parameters of the CDR circuit (specifically the loop filter transfer function coefficients) based on the detected jitter frequency. By adjusting these parameters dynamically, the system improves jitter tolerance and reduces bit-error rates without requiring a complete redesign of the CDR architecture, thus balancing reliability improvement with complexity management.
2Reliability
If adaptive parameter adjustment is implemented, then jitter tolerance improves, but device complexity increases
Solution Approach 1:
The patent employs feedback mechanisms where the CDR circuit continuously monitors the jitter frequency in the incoming data signal and adjusts its parameters accordingly. This closed-loop feedback system enables adaptive parameter adjustment that improves jitter tolerance while controlling complexity through efficient feedback processing and parameter update strategies.
Solution Approach 2:
The CDR circuit performs self-adjustment by automatically detecting jitter frequency and modifying its own parameters without external intervention. This self-service capability improves jitter tolerance while minimizing the need for additional control circuitry, as the system adapts autonomously based on its operating conditions.
3Ease of manufacture
If fixed loop gains are used, then ease of manufacture is improved, but bit-error rates increase under varying jitter conditions
Solution Approach 1:
The patent transitions from fixed loop gains to dynamically adjustable loop gains that adapt to jitter frequency. This dynamic adjustment capability reduces bit-error rates under varying jitter conditions while maintaining ease of manufacture through systematic implementation of the adaptation mechanism within the existing CDR architecture.
Solution Approach 2:
The patent modifies the loop filter transfer function parameters based on detected jitter frequency, enabling the CDR circuit to maintain optimal performance across different jitter conditions. This parameter adaptation approach improves reliability by reducing bit-error rates while keeping the manufacturing process manageable through structured parameter adjustment rather than complete circuit redesign.
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.