Differential Comparator Circuit for Stable Threshold A/D Conversion
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Solution Overview
Problem
Conventional chopper comparator circuits are susceptible to power-supply fluctuations, which affect the logical threshold and lead to inaccurate comparison operations.
Innovation Solution
A comparator circuit configuration using a differential amplifier with switch sections and a capacity section to stabilize the logical threshold, reducing the influence of power-supply fluctuations, includes a first switch section for signal voltage, a second switch section for control waveform, a capacity section connected to both, and a third switch section for short-circuiting the differential amplifier's input and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional chopper comparator circuit using an inverter circuit is used, then the circuit structure is simple, but the logical threshold changes due to power-supply fluctuations, leading to inaccurate comparison operations
Solution Approach 1:
The patent changes the fundamental operating parameter of the comparator by replacing the inverter-based logical comparison with a differential amplifier-based analog voltage comparison. This parameter change from digital logic to analog differential amplification makes the comparison operation immune to power-supply fluctuations, as the differential amplifier compares voltage differences directly rather than relying on logical thresholds that are sensitive to supply voltage changes.
Solution Approach 2:
The patent introduces a differential amplifier as an intermediary component between the input signals and the output. This differential amplifier acts as a mediator that processes the voltage difference between the signal voltage and control waveform in a manner that is independent of power-supply fluctuations, thereby improving comparison accuracy without significantly increasing overall circuit complexity.
2Measurement precision
If the logical threshold is stabilized to reduce power-supply fluctuation influence, then comparison accuracy improves, but circuit complexity increases
Solution Approach 1:
The patent achieves logical threshold stabilization by fundamentally changing the comparison mechanism from inverter-based logic to differential amplifier-based analog comparison. This parameter change eliminates the threshold drift problem inherent in inverter circuits while maintaining a relatively simple circuit structure using standard differential amplifier topology.
Solution Approach 2:
The patent employs feedback mechanisms within the differential amplifier configuration to maintain stable operation. The differential amplifier inherently provides negative feedback through its configuration, which stabilizes the operating point and eliminates the need for additional threshold-stabilization components, thereby improving accuracy without excessive complexity increase.
Data Source
AI summary
A comparator circuit according to the present disclosure includes a first switch section that selectively takes in a signal voltage, a second switch section that selectively takes in a control waveform, a differential amplifier including a non-inverted input end connected to each of output ends of the first switch section and the second switch section, a capacity section including one end connected to an inverted input end of the differential amplifier and the other end supplied with a reference voltage, and a third switch section that selectively short-circuits the inverted input end and an output end of the differential amplifier.