Differential Signal Detection Circuit for High-Voltage Switching Nodes
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Solution Overview
Problem
Conventional signal detection circuits face challenges in miniaturization and detection accuracy due to the need for high withstand voltage elements when dealing with high voltage applications, and the use of external or internal capacitors for voltage division leads to increased circuit size and parasitic capacitance issues.
Innovation Solution
A signal detection circuit with a differential configuration, utilizing two capacitors connected to the main terminals of a switching element, which input signals in a differential manner to reduce the adverse effects of parasitic capacitance and allow for integration without increasing circuit size, while also incorporating a reset function to cancel output offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high withstand voltage elements are used in conventional signal detection circuits, then detection capability for high voltage applications is improved, but circuit size increases and miniaturization becomes difficult
Solution Approach 1:
The circuit is divided into two separate detection paths: one for detecting the potential of the first main terminal and another for detecting the potential of the second main terminal. Each path uses its own capacitor and detection circuit, allowing independent optimization of each detection channel and enabling miniaturization while maintaining high voltage detection capability
Solution Approach 2:
Capacitors are introduced as intermediary elements to couple the main terminals to the detection circuits. These capacitors block high voltage DC components while allowing AC signal components to pass, enabling the use of lower withstand voltage detection circuits that can be miniaturized, thus resolving the contradiction between detection capability and circuit size
2Stress or pressure
If external or internal capacitors are used for voltage division in conventional circuits, then voltage scaling is achieved, but parasitic capacitance increases and detection accuracy deteriorates
Solution Approach 1:
The voltage division function is extracted from the detection path by using capacitors connected to the main terminals that couple signal components to the detection circuits without requiring voltage division through additional capacitors in the signal path. This removes the source of parasitic capacitance while maintaining voltage scaling capability
Solution Approach 2:
The conventional voltage division mechanism using resistive or capacitive dividers is replaced with a capacitive coupling mechanism where capacitors transfer signal components to the detection circuits. This substitution eliminates the parasitic capacitance issues associated with voltage division while preserving the voltage scaling function
3Device complexity
If conventional detection circuits are used, then circuit structure is simple, but offset errors occur and detection accuracy is reduced
Solution Approach 1:
The detection circuits are configured with different local characteristics: one detection circuit detects the potential of the first main terminal while the other detects the potential of the second main terminal. This local differentiation allows each detection path to be optimized for its specific function, reducing offset errors through differential measurement while maintaining relatively simple overall circuit structure
Data Source
AI summary
A signal detection circuit includes: a first capacitor having a first terminal connected with a first main terminal of a switching element; a second capacitor having a first terminal connected with a second main terminal of the switching element; and a detection circuit having a differential circuit configuration. The detection circuit receives, as input signals, a signal from a second terminal of the first capacitor and a signal from a second terminal of the second capacitor, detects detection target signals based on the input signals. The detection target signals include a signal of the first main terminal of the switching element and a signal of the second main terminal of the switching element.