SerDes Receiver Jitter Injection for Faster BER Calibration
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Solution Overview
Problem
In serializer-deserializers (SerDes), maintaining signal integrity across high-speed communication links is challenging due to impairments like ISI and noise, especially at high data rates, and existing optimization methods are inefficient, particularly in low loss channels where BER measurement is time-consuming and prone to fluctuations.
Innovation Solution
A self-stress check mechanism in the SerDes receiver is introduced, using a jitter injection technique to rapidly determine bit error rate (BER) and optimize system parameters, allowing for faster and more accurate calibration and adaptation of system settings without disrupting signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional BER measurement methods are used in low loss channels, then measurement accuracy can be maintained, but the measurement process becomes extremely time-consuming and prone to fluctuations
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing lookup tables (LUTs) that contain pre-determined BER values corresponding to different stress levels and system parameter combinations. During actual operation, instead of performing time-consuming BER measurements, the system simply queries these pre-computed tables to obtain BER metrics instantly, thereby resolving the contradiction between measurement accuracy and time consumption.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing lookup tables (LUTs) that contain pre-determined BER values corresponding to different stress levels and system parameter combinations. During actual operation, instead of performing time-consuming BER measurements, the system simply queries these pre-computed tables to obtain BER metrics instantly, thereby resolving the contradiction between measurement accuracy and time consumption.
2Reliability
If system parameters are finely tuned to optimize link quality, then signal integrity improves, but the narrow link margins make tuning difficult and risky during link operation
Solution Approach 1:
The patent applies preliminary action by pre-determining optimal system parameter settings through stress-free calibration procedures performed before normal operation. These pre-optimized parameters are stored and automatically applied during link training and adaptation, eliminating the need for risky real-time tuning and ensuring signal integrity without operational disruption.
Solution Approach 2:
The patent introduces a stress-free calibration mode as an intermediary procedure that separates the parameter optimization process from normal link operation. This intermediary calibration phase allows safe exploration and tuning of system parameters without risking signal integrity, and the optimized parameters are then locked in for stable operation.
3Measurement precision
If a second channel is added to enable stress check mechanisms, then BER measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the existing single communication channel to serve multiple functions: it simultaneously carries out normal data transmission and stress-induced BER measurement tasks. By making the channel multi-functional, the patent eliminates the need for a dedicated second measurement channel, thereby maintaining measurement accuracy while avoiding increased device complexity.
Solution Approach 2:
The patent merges the BER measurement function with the existing data transmission channel by superimposing stress patterns on the normal data stream. This combining of functions allows the system to perform accurate BER measurements using the same physical infrastructure, avoiding the complexity overhead of adding separate measurement channels.
Data Source
AI summary
Devices and methods are provided for performing a high-frequency jitter self stress check on a receiver to assist with optimization. High-frequency jitter is injected into a clock signal recovered from a received data signal and used to sample the data signal. The injected jitter increases the bit error rate (BER), making BER a more useful and quicker optimization metric in applications using low-noise communication links. Error correction is used to maintain acceptable output BER while the self stress check is in progress.