Retimer Clock Phase Selection for Low-Latency Data Handoff
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Solution Overview
Problem
Retimer circuitry faces challenges in reducing latency and jitter in data transmission as the distance between transmitter and receiver circuitry increases, leading to transmission errors, which existing technologies have not adequately addressed.
Innovation Solution
The system employs a retimer circuitry with advanced clock generation and handoff mechanisms, including interleaving circuitry, comparison circuitry, and flip-flops, to generate multiple receiver clocks with different phase shifts, allowing for deterministic latency and reduced jitter by selecting the optimal receiver clock for data conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If data is transmitted over long distances, then transmission range is increased, but transmission errors increase due to jitter and latency
Solution Approach 1:
A retimer circuit is introduced as an intermediary device between the transmitter and receiver. The retimer receives data from the transmitter, performs clock domain conversion using multiple phase-shifted receiver clocks, and retransmits the data with reduced jitter to the receiver. This intermediary effectively breaks the direct long-distance transmission path into two segments, each with better signal integrity.
Solution Approach 2:
The patent changes the clock parameter by generating multiple receiver clocks with different phase shifts (e.g., 0°, 90°, 180°, 270°). By selecting the optimal phase-shifted clock that best aligns with the incoming data, the system adapts to timing variations caused by long-distance transmission, thereby reducing jitter and improving reliability.
2Length of stationary object
If traditional retimer circuitry is used, then transmission range is extended, but latency and jitter are not sufficiently reduced
Solution Approach 1:
The clock generation function is segmented into multiple parallel paths, each producing a phase-shifted version of the base clock. Instead of using a single clock domain conversion path that introduces variable latency, the segmented approach with multiple fixed-phase clocks allows for deterministic and minimized latency by selecting the best-matching phase.
Solution Approach 2:
The system dynamically selects the optimal receiver clock phase based on real-time comparison of signal quality metrics. This dynamic adaptation allows the retimer to minimize latency and jitter by choosing the most appropriate clock phase for current transmission conditions, rather than using a fixed single-phase approach.
3Reliability
If multiple receiver clocks with different phase shifts are generated, then latency and jitter are reduced, but device complexity increases
Solution Approach 1:
Multiple phase-shifted clock signals are generated by combining a base clock with phase-shift network circuitry. Rather than generating each clock independently, the system merges the clock generation function into a unified circuit that produces all required phases from a single source, reducing overall circuit complexity while maintaining multiple clock options.
4Reliability
If data is retransmitted with reduced jitter, then transmission reliability is improved, but transmission speed may be affected
Solution Approach 1:
The retimer operates continuously without interrupting the data flow. By maintaining continuous clock domain conversion using pre-generated phase-shifted clocks, the system avoids speed penalties associated with re-synchronization or buffer flushing, ensuring that transmission speed is preserved while improving reliability through jitter reduction.
Data Source
AI summary
An example system includes: interleaving circuitry including a data input, a plurality of data outputs, and a plurality of clock inputs, the data input coupled to the received data input and each of the plurality of clock inputs coupled to one of the plurality of receiver clock outputs; and handoff circuitry coupled to the interleaving circuitry, the handoff circuitry including: comparison circuitry coupled to the clock generation circuitry and configured to compare the plurality of receiver clocks to the transmission clock; clock configuration circuitry coupled to the comparison circuitry and configured to select one of the plurality of receiver clocks based on the comparison circuitry; and a plurality of flip-flops coupled to the clock configuration circuitry and configured to convert the plurality of data outputs from the plurality of receiver clocks to the transmission clock to generate a plurality of transmission data streams based on the one of the plurality of receiver clocks selected by the clock configuration circuitry.