Clock Data Recovery Convergence via Signed Timing Injection
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Solution Overview
Problem
Clock and data recovery systems in communication channels face challenges with slow convergence due to initial sampling phase errors and frequency offsets, leading to prolonged convergence times, especially when the initial sampling phase is offset from the optimal phase or when there are large frequency differences between transmitter and receiver clocks.
Innovation Solution
The implementation of an error detection mechanism that injects an additional increment into the clock and data recovery timing estimate based on the sign and direction of the accumulated gradient value, improving convergence by accelerating the clock and data recovery process, and allowing for programmable configuration and control without relying on preamble sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional clock and data recovery systems are used without timing injection, then the system structure remains simple, but the convergence time is prolonged due to initial sampling phase errors and frequency offsets
Solution Approach 1:
The patent applies preliminary action by injecting a timing estimate into the clock and data recovery system before full convergence occurs. The timing injection mechanism provides advance correction based on accumulated gradient values, allowing the system to jump-start the convergence process and avoid the slow initial phase of conventional CDR operation. This preliminary timing correction significantly reduces convergence time without requiring complete system redesign.
Solution Approach 2:
The patent introduces an intermediary timing injection mechanism that acts as a mediator between the phase detector output and the clock recovery process. The timing injection unit processes accumulated gradient values and injects corrected timing estimates into the CDR loop, serving as an intermediate correction layer that accelerates convergence without directly modifying the core CDR architecture. This intermediary approach adds minimal complexity while achieving significant performance improvement.
2Speed
If timing injection is implemented to accelerate convergence, then convergence speed improves, but the device complexity increases due to additional injection mechanisms
Solution Approach 1:
The patent applies universality by designing the timing injection mechanism to perform multiple functions within a single integrated structure. The timing injection unit not only accelerates convergence but also continuously corrects timing errors during normal operation, and can adapt to different data rates and channel conditions. This multi-functional design reduces the need for separate correction circuits and minimizes overall device complexity while maintaining high convergence speed.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the timing injection magnitude and frequency based on accumulated gradient values and system state. The injection strength is modulated according to the detected timing error magnitude, allowing the system to apply stronger corrections during initial convergence and weaker corrections during steady-state operation. This adaptive parameter adjustment optimizes convergence speed while minimizing the complexity of the injection mechanism.
Data Source
AI summary
A system for data and clock recovery includes a timing error detector, a phase detector, and a phase increment injector. The phase increment injector may be used to determine an increment to affect an output of the phase detector or a clocking element. A sign of the increment is determined from a sign or direction of an accumulated version of a clock and data recovery gradient value.