Differential Amplifier Biasing for Common-Mode Transient Isolation
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Solution Overview
Problem
Existing digital isolators suffer from abnormal signal transmission due to direct-current offset voltages caused by common-mode interference, which reduces amplifier gain and output swing.
Innovation Solution
A differential signal amplification circuit with a multi-stage differential amplifier and a common-mode transient adaptive biasing circuit that detects and compensates for common-mode interference by providing biasing currents to the differential amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If common-mode transient interference signals occur, then direct-current offset voltages are generated on the resistors, but the amplifier gain and output swing are reduced resulting in abnormal signal transmission
Solution Approach 1:
The patent implements a feedback mechanism where the common-mode detection circuit continuously monitors the common-mode voltage at the amplifier input and adjusts the biasing current accordingly. When common-mode transient interference is detected, the system automatically compensates by adjusting the biasing current to maintain proper amplifier operation, thereby resolving the contradiction between signal transmission stability and susceptibility to offset voltages.
Solution Approach 2:
The system performs self-diagnosis and self-correction through the common-mode detection circuit that automatically detects interference conditions and adjusts the biasing current without external intervention. This self-service mechanism enables the amplifier to maintain optimal performance under varying common-mode voltage conditions, eliminating the harmful effects of direct-current offset voltages while preserving signal transmission reliability.
2Reliability
If the biasing current is increased to compensate for common-mode interference, then the amplifier gain is maintained, but the power consumption increases
Solution Approach 1:
The patent employs dynamic adjustment of the biasing current based on real-time detection of common-mode voltage conditions. Rather than using a fixed high biasing current that would continuously increase power consumption, the system dynamically adapts the current level - increasing it only when common-mode transient interference is detected and maintaining normal levels during stable operation. This dynamic approach preserves amplifier gain stability while minimizing unnecessary power consumption.
Data Source
AI summary
The present invention discloses a differential signal amplification circuit as well as a digital isolator and a digital receiver applying the differential signal amplification circuit, wherein the differential signal amplification circuit includes a multi-stage differential amplifier and a common-mode transient adaptive biasing circuit. The common-mode transient adaptive biasing circuit is configured to detect a positive or negative common-mode transient interference signal at a positive input terminal and a negative input terminal, and provide a biasing current of a differential amplifier of at least one stage above a second stage when the positive or negative common-mode transient interference signals are detected. With the technical solutions of the present invention, abnormal signal transmission caused by the common-mode interference signals can be suppressed.