Chopper Voltage Comparator Circuit Offset Correction
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Solution Overview
Problem
Voltage comparators face precision degradation due to input offset voltage when amplifying minute voltages, making it challenging to accurately compare voltages in the range of several μV to hundreds mV with a threshold voltage.
Innovation Solution
A voltage comparator circuit design that includes an amplifier circuit, an input switch circuit, a chopper inverter type comparator, and a voltage source, which alternates phases to correct for amplifier offset, allowing precise comparison of voltage differences between input terminals and a threshold voltage without being affected by amplifier offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an amplifier is arranged at the front end of the voltage comparator to amplify minute voltages, then the ability to compare small voltages is improved, but the input offset voltage of the amplifier degrades the precision of the voltage comparator circuit
Solution Approach 1:
The patent employs periodic action by alternating between a first phase (amplification phase) and a second phase (correction phase) through switches. In the first phase, the amplifier amplifies the voltage difference between input terminals. In the second phase, the amplified voltage is fed back to the inverting input terminal to cancel the offset voltage. This periodic switching enables the system to achieve high precision voltage comparison by eliminating the harmful offset effect.
Solution Approach 2:
The patent implements feedback by connecting the output of the amplifier through a switch to the inverting input terminal of the same amplifier. During the correction phase, the amplified voltage is fed back to counteract the input offset voltage. This feedback mechanism allows the system to automatically compensate for the offset, thereby improving measurement precision without requiring additional correction circuits.
2Measurement precision
If the amplifier amplifies minute voltage differences, then the sensitivity of voltage detection is improved, but the offset voltage causes measurement errors
Solution Approach 1:
The system uses periodic switching between measurement phase and correction phase. During the measurement phase, the amplifier detects minute voltage differences with high sensitivity. During the correction phase, the stored amplified voltage is applied to cancel the offset. This periodic operation preserves measurement accuracy by systematically removing offset errors while maintaining high sensitivity during detection.
Solution Approach 2:
The patent discards the offset voltage component by separating it from the useful signal through periodic operation. The offset voltage is amplified along with the signal during the first phase, then the amplified version is recovered and used in the second phase to cancel the offset. This process effectively discards the harmful offset information while recovering and utilizing it for correction purposes.
Data Source
AI summary
The present disclosure provides a voltage comparator circuit, a power management circuit and an electronic device. The voltage comparator circuit compares a voltage difference between a positive electrode input terminal and a negative electrode input terminal with a threshold voltage. An amplifier circuit includes a first input node and a second input node, and amplifies a voltage difference between the first input node and the second input node. The input switch circuit, in a first phase, applies a predetermined voltage of one of the positive electrode input terminal and the negative electrode input terminal to the first input node and the second input node of the amplifier circuit; and in a second phase, applies a voltage of the positive electrode input terminal to the first input node of the amplifier circuit, and applies a voltage of the negative electrode input terminal to the second input node.