Current-Feedback Linear Power Circuit for Fast Load Response
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Solution Overview
Problem
Existing linear power circuits face challenges in achieving stable and fast load response characteristics, often resulting in significant overshoot and undershoot when load currents change, which can be exacerbated by the use of voltage feedback operational amplifiers.
Innovation Solution
A linear power circuit design incorporating a current feedback operational amplifier with a bias circuit, third and fourth current mirror circuits, and an external output capacitor for phase compensation, which increases output impedance and reduces overshoot and undershoot by using a class AB amplifier configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage feedback operational amplifiers are used in linear power circuits, then the circuit can provide basic amplification function, but the load response characteristics deteriorate with significant overshoot and undershoot when load currents change
Solution Approach 1:
The patent changes the feedback parameter from voltage feedback to current feedback, fundamentally altering the operational amplifier's feedback mechanism. This parameter change enables the circuit to respond faster to load current changes while maintaining output voltage stability, resolving the contradiction between reliability and speed.
Solution Approach 2:
The patent implements current feedback through the negative input terminal instead of voltage feedback, creating a feedback loop that directly responds to load current changes. This feedback mechanism actively compensates for load variations, reducing overshoot and undershoot while maintaining stable output voltage.
2Speed
If linear power circuits are designed for fast load response, then the response speed improves, but the overshoot and undershoot increase significantly
Solution Approach 1:
The patent changes the feedback parameter from voltage feedback to current feedback, fundamentally altering the operational amplifier's feedback mechanism. This parameter change enables the circuit to respond faster to load current changes while maintaining output voltage stability, resolving the contradiction between reliability and speed.
Solution Approach 2:
The patent implements current feedback through the negative input terminal instead of voltage feedback, creating a feedback loop that directly responds to load current changes. This feedback mechanism actively compensates for load variations, reducing overshoot and undershoot while maintaining stable output voltage.
3Device complexity
If conventional linear power circuit configurations are used, then the design is simpler, but the load response characteristics and overshoot/undershoot performance worsen
Solution Approach 1:
The patent changes the feedback parameter from voltage feedback to current feedback, fundamentally altering the operational amplifier's feedback mechanism. This parameter change enables the circuit to respond faster to load current changes while maintaining output voltage stability, resolving the contradiction between reliability and speed.
Solution Approach 2:
The patent implements current feedback through the negative input terminal instead of voltage feedback, creating a feedback loop that directly responds to load current changes. This feedback mechanism actively compensates for load variations, reducing overshoot and undershoot while maintaining stable output voltage.
Data Source
AI summary
The present disclosure provides a linear power circuit. The linear power circuit includes an input unit, a current-voltage converter, a voltage-current converter and an output unit. The input unit is configured to receive an input signal and output a first current signal. The current-voltage converter is configured to convert the first current signal into a first voltage signal. The voltage-current converter is configured to convert the first voltage signal into a second current signal. The output unit is configured to generate an output current signal from the second current signal using a current mirror circuit and output the output current signal to an output terminal. The input unit and the current-voltage converter constitute a current feedback operational amplifier.