Chopper Amplifier Switch Timing to Reduce Input Current
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Solution Overview
Problem
Chopper amplifiers experience increased input currents during modulating operations, leading to voltage drops and reduced accuracy due to input current-induced voltage drops.
Innovation Solution
A chopper stabilized amplifier design incorporating a switch circuit between the input unit and the chopper, utilizing control signals to minimize input currents by adjusting the timing and overlap of control signals to reduce current flow through MOS transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a chopper performs a modulating operation to reduce noise and offset voltage, then amplification accuracy is improved, but input currents increase causing voltage drops
Solution Approach 1:
A switch circuit is introduced as an intermediary component between the input unit and the chopper. This switch circuit, controlled by a second control signal, selectively connects or disconnects the input terminals to the chopper, thereby reducing input currents during modulating operations while preserving the chopper's noise and offset reduction capabilities
2Measurement precision
If input currents are reduced by adjusting control signal timing, then voltage accuracy is improved, but device complexity increases
Solution Approach 1:
The switch circuit operates periodically based on a second control signal that is synchronized with the chopper's modulating operation. By timing the switch circuit's operation to coincide with the chopper's control signals, input currents are reduced during critical periods while maintaining simplicity through periodic rather than continuous control
Data Source
AI summary
According to one embodiment, a chopper stabilized amplifier includes an input unit, a first chopper, a first amplifier, and a switch circuit. The input unit receives a differential input signal at a first input terminal and a second input terminal. The first chopper modulates the differential input signal based on a first control signal and an inverse signal of the first control signal. The first amplifier amplifies the signals with the modulated differential output from the first chopper. The switch circuit is provided between the input unit and the first chopper, and receives a second control signal and reduces input currents which flow in the first chopper when the first chopper performs a modulating operation, by using an operation with the second control signal.