Differential Switched-Capacitor Amplifier for Stable Common Voltage
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Solution Overview
Problem
Conventional switched capacitor amplifiers experience errors due to large impedance ratios between differential input terminals, leading to fluctuations in common voltage and uneven settling times, especially when input levels vary.
Innovation Solution
A fully differential switched capacitor amplifier design incorporates differential input resistors between the differential input switches and sampling capacitors, reducing the impedance ratio and stabilizing the common voltage by equalizing settling times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional switched capacitor amplifier configuration is used, then the circuit structure is simple, but large impedance ratios between differential input terminals cause errors and settling time differences
Solution Approach 1:
A differential input resistor is introduced as an intermediary component connected between the differential input terminal and the sampling capacitor. This resistor acts as a mediator to balance the impedance ratios between differential input terminals, thereby reducing errors and settling time differences without significantly complicating the overall circuit structure
Solution Approach 2:
The impedance ratio between differential input terminals is modified by adding the differential input resistor. This parameter change directly addresses the source of errors and settling time discrepancies, improving measurement precision while maintaining circuit simplicity
2Stability of the object's composition
If differential input terminals are used without additional components, then the circuit is simple, but common voltage fluctuates and settling times become uneven
Solution Approach 1:
The differential input resistor serves as a stabilizing intermediary that equalizes the impedance paths for differential signals. This mediation prevents common voltage fluctuations and ensures uniform settling times across differential inputs, achieving stability without excessive circuit complexity
3Measurement precision
If sampling capacitor directly connects to differential input terminal, then parasitic load is minimized, but impedance ratio causes errors
Solution Approach 1:
The differential input resistor is positioned as an intermediary between the differential input terminal and the sampling capacitor. This placement allows it to correct impedance ratio errors while introducing minimal additional parasitic load, preserving signal sampling accuracy
Solution Approach 2:
By changing the impedance parameters through the addition of the differential input resistor, the system achieves more accurate signal sampling. The resistor's value is selected to optimize the balance between error reduction and parasitic load minimization
Data Source
AI summary
A fully differential switched capacitor amplifier receives a differential analog signal from a differential input terminal, amplifies the differential analog signal, and outputs an amplified signal from a differential output terminal. The fully differential switched capacitor amplifier includes: a sampling capacitor that respectively samples the differential analog signal input from the differential input terminal; a differential input switch connected to a path for inputting the differential analog signal between the differential input terminal and the sampling capacitor; a fully differential amplifier that amplifies the differential analog signal input to the sampling capacitor; and a differential input resistor connected between the differential input switch and the sampling capacitor.