Timing Recovery Loop Acceleration for Faster Phase and Frequency Tracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Timing recovery circuits in high-speed serializers/deserializers face latency issues due to processing delays in loop filtering, which reduce loop bandwidth and jitter tolerance, making them less power-efficient and cost-effective.
Innovation Solution
Incorporating phase and frequency tracking accelerators into the timing recovery circuit to compute phase and frequency variations during the delay period of the loop filter, either in direct-form or using pre-computed look-up tables, to eliminate processing delays and enhance loop bandwidth and jitter tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If additional delay stages are inserted into critical paths to ease timing closure, then setup and hold time requirements are met, but loop latency increases and processing speed decreases
Solution Approach 1:
The patent pre-computes phase and frequency variations during the delay period using accelerators that operate in parallel with the loop filter. By performing the tracking computation beforehand and storing results in buffers, the system eliminates the need for additional delay stages while meeting timing requirements.
2Speed
If high-speed cells are used instead of low-speed cells, then setup and hold time requirements are met, but power consumption increases
Solution Approach 1:
The patent divides the timing recovery function into two independent segments: the loop filter that maintains original speed characteristics, and the phase/frequency tracking accelerators that operate in parallel. This segmentation allows low-speed cells to be used in the main path while power consumption remains controlled.
3Reliability
If loop bandwidth is increased to improve jitter tolerance, then tracking performance improves, but loop latency increases and stability decreases
Solution Approach 1:
The patent introduces phase and frequency tracking accelerators as intermediary components that compute tracking variations during the loop filter delay period. These accelerators act as mediators that provide advance compensation for phase and frequency changes, allowing the loop to respond faster without increasing overall latency or compromising stability.
4Productivity
If processing delay of loop filtering is reduced to accelerate phase tracking, then loop bandwidth increases, but timing closure becomes more difficult
Solution Approach 1:
The patent creates a parallel copy of the tracking function through accelerators that compute phase and frequency variations independently during the delay period. This copying approach allows the main loop filter to maintain its original processing delay while the accelerators provide accelerated tracking information, avoiding timing closure issues.
Data Source
AI summary
Circuit and methods accelerate jitter tracking and reduce or eliminate the processing delay of loop filtering in timing recovery. A timing recovery circuit incorporates a phase tracking accelerator and a frequency tracking accelerator to compute the phase and frequency variation of incoming signal during the delay period of a loop filter. In one embodiment, phase and frequency tracking accelerators are realized in direct forms. In another embodiment, pre-computed look-up tables are employed in phase and frequency tracking accelerators to ease timing closure and simplify accelerator circuit. The phase tracking accelerator and the frequency tracking accelerator together compensate the estimated phase at the output of a loop filter and eliminate the processing delay of loop filtering. The loop bandwidth and jitter tolerance of timing recovery are increased.