Linear Power Supply Circuit Current Feedback Phase Compensation
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Solution Overview
Problem
Existing linear power supply circuits face difficulties in obtaining desired frequency characteristics due to phase lags caused by feeding regulated output voltage information back to amplifiers, requiring additional phase compensation circuits or larger output capacitors.
Innovation Solution
A linear power supply circuit design that includes an output transistor, a driver, and a feedback circuit which feeds back information on output current to the driver, allowing it to drive the transistor based on the difference between output and reference voltages, and utilizing a differential amplifier, current amplifier, and phase compensation circuit to control frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If output voltage information is fed back to the amplifier, then voltage regulation is achieved, but phase lags occur and frequency characteristics deteriorate
Solution Approach 1:
The patent implements feedback by feeding back output current information to the driver, which controls the output transistor based on both voltage difference and current feedback. This current feedback mechanism provides a different feedback path that avoids the phase lag issues associated with voltage feedback through the amplifier, thereby maintaining both regulation precision and frequency characteristics
Solution Approach 2:
The patent introduces a current feedback path as an intermediary mechanism. Instead of directly feeding back voltage information through the amplifier chain, the system uses a separate current sensing path that feeds current information to the driver, acting as an intermediary to achieve regulation without the phase lag problems
2Reliability
If phase compensation circuit or larger output capacitor is added, then frequency characteristics improve, but device complexity increases
Solution Approach 1:
The patent extracts the phase compensation function from the traditional voltage feedback path and implements it through a separate current feedback path. By taking out the phase compensation requirement from the main amplifier chain and handling it through current feedback to the driver, the system achieves desired frequency characteristics without adding complex phase compensation circuits or large output capacitors
Data Source
AI summary
A linear power supply circuit according to the present invention is provided with: an output transistor provided between an input end to which an input voltage is applied and an output end to which an output voltage is applied; a driver for driving the output transistor; and a feedback unit for feeding, back to the driver, information about an output electrical current that is output from the output end. The driver drives the output transistor on the basis of the difference between a voltage based on the output voltage and a reference voltage, as well as the information.