Switched Capacitor Op-Amp Output Stage for Rail-to-Rail Signal Swing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional signal output circuits require a separate charge pump circuit to generate positive or negative power supply voltages for operational amplifiers to achieve output signal amplitudes exceeding the power supply voltage or falling below ground voltage, resulting in a larger circuit scale.
Innovation Solution
The implementation of a switched capacitor output stage in the operational amplifier, which samples and transfers differential voltage between the input voltage and a given voltage, allowing the operational amplifier to output signal amplitudes exceeding the power supply voltage or falling below ground voltage without a separate voltage generation circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a separate charge pump circuit is used to generate positive or negative power supply voltage for the operational amplifier, then the output signal amplitude can exceed the power supply voltage or fall below ground voltage, but the circuit scale becomes large
Solution Approach 1:
The charge pump circuit is merged with the operational amplifier by integrating it as the output stage of the op-amp. The switched capacitor circuit, which functions as a charge pump, is incorporated directly into the operational amplifier structure, eliminating the need for a separate voltage generation circuit while maintaining the capability to output signals exceeding the power supply voltage
Solution Approach 2:
The switched capacitor output stage serves multiple functions: it acts as both the output stage of the operational amplifier and the voltage generation circuit (charge pump). This multi-functional design allows the same circuit block to perform both signal amplification and voltage boosting, reducing overall circuit complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables the operational amplifier to produce output signal amplitudes exceeding the power supply voltage or falling below ground voltage without the need for a separate charge pump circuit, reducing circuit complexity and size while maintaining efficient signal processing.
Implementation Method 1
a capacitor configured to sample differential voltage between input voltage outputted from the amplification stage and given voltage other than the input voltage
Implementation Method 2
the switched capacitor circuit transfers the differential voltage sampled by the capacitor by switching of the switches
Data Source
AI summary
An object is to output output signal amplitude exceeding power supply voltage or output signal amplitude falling below ground voltage without requiring a charge pump circuit or the like to generate positive or negative power supply voltage for an operational amplifier. The present invention provides a signal output circuit comprising an operational amplifier including: an amplification stage configured to amplify differential input voltage; and an output stage configured to amplify an input signal amplified by the amplification stage and output the input signal as an output signal, wherein the output stage is a switched capacitor circuit which includes switches and a capacitor configured to sample differential voltage between input voltage outputted from the amplification stage and voltage other than the input voltage and which transfers the differential voltage sampled by the capacitor by switching of the switches based on the input voltage.