Sense Amplifier Offset Correction Without Multiplexer Loading
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Solution Overview
Problem
Existing data communication systems, particularly sense amplifiers, are inadequate for high-data communication applications due to inefficiencies and added capacitance from multiplexers, which degrade performance and bandwidth.
Innovation Solution
An offset correction technique for SERDES systems involves setting a CTLE module to isolation mode, where sense amplifiers sample data asynchronously to determine an offset value, eliminating the need for additional components and reducing undesirable effects from multiplexers by using existing CTLEs and sense amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiplexers are added to enable offset correction in sense amplifiers, then offset correction capability is improved, but device complexity and bandwidth are degraded due to added capacitance
Solution Approach 1:
The patent merges the offset correction function with the existing CTLE and sense amplifier components. The CTLE is configured to operate in both normal mode (for signal equalization) and isolation mode (for offset sampling), eliminating the need for separate multiplexer components. This integration approach maintains offset correction capability while reducing device complexity and avoiding the bandwidth degradation caused by multiplexer capacitance.
Solution Approach 2:
The CTLE is designed with multi-functionality to perform both signal equalization during normal operation and offset sampling during isolation mode. By making the CTLE universal, the patent eliminates the need for dedicated offset correction components like multiplexers, thereby reducing device complexity while maintaining the required offset correction precision.
2Measurement precision
If multiplexers are added for offset correction, then offset correction capability is improved, but power consumption increases
Solution Approach 1:
The patent combines the offset correction function with existing power-efficient components (CTLE and sense amplifier). By avoiding the addition of multiplexer components, the design prevents the associated power consumption increase, achieving offset correction capability without the penalty of higher power usage.
Solution Approach 2:
The sense amplifier performs offset sampling during isolation mode using its own existing circuitry without requiring additional active components. This self-service approach allows offset correction to be achieved without the extra power consumption that would result from activating additional multiplexer components.
3Measurement precision
If CTLE is shut during isolation mode, then offset sampling accuracy is improved by reducing capacitive coupling noise, but signal equalization is temporarily suspended
Solution Approach 1:
The patent implements periodic switching between normal mode (for signal equalization) and isolation mode (for offset sampling). The CTLE alternates between these modes, temporarily suspending equalization during brief isolation periods to perform accurate offset sampling, then resuming equalization. This periodic action achieves high-precision offset correction while maintaining overall system productivity through rapid mode switching.
Solution Approach 2:
The offset sampling operation is performed in advance during isolation mode before normal signal equalization resumes. By completing the offset measurement preliminarily, the system ensures accurate offset values are available for subsequent equalization operations, improving overall processing efficiency despite the temporary suspension of equalization.
Data Source
AI summary
The present invention is directed to data communication. More specifically, embodiments of the present invention provide an offset correction technique for a SERDES system. A CTLE module for receiving input data signal is set to an isolation mode, and one or more sense amplifiers perform data sampling asynchronously during the isolation mode. During the isolation mode, CLTE(s) that are not directly connected to the sense amplifiers are shut. Data sampled during the isolation mode are used to determine an offset value that is later used in normal operation of the SERDES system. There are other embodiments as well.