Transmitter Pre-Distortion Circuit for SerDes Signal Integrity
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Solution Overview
Problem
High-bandwidth data transfer systems, such as SerDes, face challenges in achieving error rates below 10^-17 due to channel attenuation and crosstalk, requiring flexible pre-distortion to compensate for signal distortions introduced during transmission, but existing solutions lack independence in adjusting pre-cursor, cursor, and post-cursor levels.
Innovation Solution
A circuit and method that provide complete flexibility in setting pre-cursor, cursor, and post-cursor levels by using multiple drivers with independent control signals, allowing for adjustments to each component independently to compensate for channel impairments, implemented in a SerDes system with digital equalization techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple drivers are used to provide pre-distortion signals, then flexibility in adjusting pre-cursor, cursor, and post-cursor levels is improved, but device complexity increases
Solution Approach 1:
The pre-distortion circuit is segmented into multiple independent driver circuits (first driver for pre-cursor, second driver for cursor, third driver for post-cursor), each controlled by separate control signals. This segmentation allows independent adjustment of each signal level while maintaining manageable circuit complexity through functional decomposition.
Solution Approach 2:
The driver circuits are designed with dynamic control capabilities, where each driver can independently adjust its output level based on control signals. The circuit transitions from static fixed-level pre-distortion to dynamic adjustable pre-distortion, enabling adaptation to different channel conditions while maintaining systematic control.
2Adaptability or versatility
If independent control signals are used for each driver, then adjustment independence is improved, but control complexity increases
Solution Approach 1:
The control system is segmented into separate control circuits for each driver, with each control circuit receiving and processing its own control signal independently. This segmentation enables independent adjustment of pre-cursor, cursor, and post-cursor levels without interfering with each other, while keeping control logic modular and manageable.
Solution Approach 2:
Each driver circuit is designed to be multi-functional, capable of responding to different control signal levels and conditions. The universal driver design allows the same basic circuit structure to handle different signal types (pre-cursor, cursor, post-cursor) with independent control, reducing overall system complexity through pattern reuse.
3Reliability
If pre-distortion is applied to compensate for channel attenuation, then signal quality is improved, but the system requires more complex equalization
Solution Approach 1:
The system applies pre-distortion to the transmitted signal before it enters the channel, anticipating and compensating for channel attenuation and distortion effects. By performing the compensation action in advance at the transmitter, the system reduces the burden on receiver-side equalization circuits, improving bit error rate performance while managing overall system complexity.
Data Source
AI summary
The present invention relates to pre-distortion in transmitter circuits and provides a circuit for introducing pre-distortion into the output of a transmitter, wherein said pre-distortion comprises a pre-cursor, a cursor and a post-cursor, the circuit comprising: a first driver arranged to switch an output drive between said pre-cursor and said cursor; a second driver arranged to switch an output drive between said post-cursor and said cursor; a third driver arranged to switch an output drive between a positive cursor drive and a negative cursor drive. The arrangement provided give flexibility when setting the pre-cursor, cursor and post-cursor levels.