Isolation Channel Direct Demodulation for Low-Delay CMTI
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Solution Overview
Problem
Conventional common mode transient suppression techniques introduce substantial delay and gaps in suppression, making systems vulnerable to fault conditions, especially in high-rate data transfer and power applications where additional propagation delay negatively impacts performance.
Innovation Solution
A bandpass filter circuit and demodulator are used to directly demodulate a data-edge-encoded signal across an isolation barrier, reducing power consumption and enhancing common-mode transient immunity through data-edge encoding and decoding schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional deglitching techniques are used to suppress common mode transient events, then common mode transient immunity is improved, but substantial propagation delay is introduced into the receiver signal path
Solution Approach 1:
The patent extracts and removes the harmful deglitching delay from the signal path by implementing direct demodulation that processes common mode transient events without introducing substantial propagation delay, thereby maintaining common mode transient immunity while eliminating the time loss associated with conventional deglitching circuits
Solution Approach 2:
The patent replaces the mechanical/electrical deglitching circuit approach with a direct demodulation method that uses signal processing techniques to achieve common mode transient suppression without the propagation delay inherent in conventional deglitching hardware
2Reliability
If multiple deglitching circuits or programmable deglitching circuits are used to cover a broader range of common mode transient events, then the range of common mode transient suppression is improved, but device complexity and propagation delay increase
Solution Approach 1:
The patent implements a universal direct demodulation approach that can suppress common mode transient events across a broad range of durations without requiring multiple specialized deglitching circuits, thereby achieving multi-functionality in a single circuit design that reduces overall device complexity
Solution Approach 2:
The patent uses parameter changes in the direct demodulation process to adapt to different common mode transient event durations, allowing a single circuit to handle a wide range of suppression requirements by adjusting processing parameters rather than requiring multiple fixed circuits
3Reliability
If deglitching circuits are used to suppress common mode transient events, then common mode transient immunity is improved, but data rate is reduced due to added propagation delay
Solution Approach 1:
The patent extracts the harmful propagation delay from the signal path by implementing direct demodulation that processes signals without the substantial delay introduced by deglitching circuits, thereby maintaining common mode transient immunity while preserving high data rate capability
4Reliability
If increased dead times are used in power stages to accommodate deglitching delay, then common mode transient immunity is improved, but performance of power stages is negatively impacted
Solution Approach 1:
The patent removes the need for increased dead times by implementing direct demodulation that does not introduce substantial propagation delay, thereby maintaining common mode transient immunity while preserving the performance and efficiency of power stages without requiring extended dead time intervals
Data Source
AI summary
An apparatus for communicating across an isolation barrier includes a differential pair of input terminals. The apparatus includes a bandpass filter circuit configured to receive a received signal on the differential pair of input terminals and to provide a received differential signal on a differential pair of nodes. The apparatus includes a demodulator directly coupled to the bandpass filter circuit and configured to directly demodulate the received differential signal on the differential pair of nodes to provide a demodulated received signal.