Multi-Threshold SerDes Receiver for Unterminated Multi-Drop Buses
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Solution Overview
Problem
The existing SOUNDWIRE audio standard faces challenges with line reflections, impedance discontinuities, and line propagation delays in unterminated, multi-drop SerDes audio bus configurations, leading to reduced bandwidth and increased bit error rates due to noise and uncertainty in signal propagation.
Innovation Solution
Implementing a multi-threshold receiver that selects additional voltage levels to trigger latching events based on differential signals, allowing for improved noise immunity and logic operations to generate outputs, thereby widening the sampling window and enhancing bandwidth without the need for termination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-threshold receivers are used in unterminated multi-drop SerDes audio bus configurations, then device complexity and power consumption are kept low, but noise immunity is poor and bit error rates increase due to line reflections and impedance discontinuities
Solution Approach 1:
The receiver's voltage detection function is segmented into multiple independent threshold comparators, each detecting a specific voltage level. This segmentation allows the receiver to identify signal transitions more reliably in the presence of reflections and impedance discontinuities, improving noise immunity without requiring complex termination circuits.
Solution Approach 2:
The invention changes the detection parameter from a single voltage threshold to multiple voltage thresholds. By monitoring transitions across several voltage levels (e.g., from logic 0 to logic 1 through intermediate levels), the receiver can distinguish valid signal transitions from noise and reflections, significantly improving reliability in unterminated bus configurations.
2Speed
If conventional single-threshold receivers are used, then device complexity is low, but bandwidth is limited due to narrow sampling windows caused by signal uncertainty
Solution Approach 1:
The sampling function is segmented across multiple voltage thresholds, creating multiple opportunities to detect valid signal transitions. This extends the effective sampling window by allowing detection at different points during signal transitions, thereby increasing bandwidth without requiring complex timing synchronization.
Solution Approach 2:
The receiver dynamically adapts its detection strategy by using multiple thresholds that can be selectively activated based on signal conditions. This dynamic approach allows the receiver to capture signals across a wider frequency range by flexibly identifying valid transitions even when signal edges are slowed by reflections or impedance mismatches.
3Reliability
If additional voltage thresholds and latching events are implemented, then noise immunity and bandwidth are improved, but power consumption increases
Solution Approach 1:
Multiple threshold detection functions are merged into a single integrated receiver circuit block. By combining the detection logic for multiple thresholds within one circuit architecture rather than using separate receiver circuits, the patent achieves improved noise immunity while minimizing the additional power overhead through shared circuit resources and efficient logic design.
4Ease of manufacture
If unterminated multi-drop configuration is used, then ease of manufacture and device count are improved, but line reflections and impedance discontinuities increase
Solution Approach 1:
The invention converts the harmful effect of line reflections into a detectable pattern by using multiple voltage thresholds. Instead of trying to eliminate reflections through termination, the receiver is designed to recognize valid signal transitions despite the presence of reflections, effectively converting this harmful phenomenon into a manageable detection challenge that can be solved through intelligent threshold monitoring.
Data Source
AI summary
Systems and methods for multi-threshold sensing at an audio receiver, and systems and methods for calibrating an audio system to optimize for the specific configuration of the audio system are disclosed herein. In some implementations of a multi-threshold receiver, at least one additional voltage level is selected to trigger latching events within the receiver based on changes of the receiver input (which includes differential signals Vp and Vn) and in turn, to generate internal signals within the multi-threshold receiver, and then logic operations are performed on these internal signals to generate the output of the multi-threshold receiver.