Dual-Loop Voltage Regulator for Gain-Phase Tradeoff
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Solution Overview
Problem
Conventional voltage regulators face a tradeoff between achieving high gain and maintaining a good phase margin, often sacrificing one for the other, which affects their ability to provide stable DC regulation and transient response.
Innovation Solution
A dual loop voltage regulator design incorporating a fast, low-gain amplifier and a slow, high-gain amplifier, where the outputs of both are summed to generate a regulated voltage, allowing for improved DC regulation, transient stability, and extended frequency bandwidth without sacrificing phase margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-gain amplifier is used to reduce DC regulation error, then DC regulation is improved, but phase margin decreases
Solution Approach 1:
The voltage regulator is divided into two separate amplifier loops: a high-gain amplifier for DC regulation and a low-gain amplifier for transient response and phase margin. This segmentation allows each amplifier to be optimized for its specific function without compromising the other, resolving the contradiction between DC regulation precision and phase margin stability.
Solution Approach 2:
The system dynamically switches between the high-gain amplifier's DC regulation capability and the low-gain amplifier's transient response capability based on the operating conditions. The control logic determines which amplifier should be active, allowing the system to adaptively maintain both high DC precision and adequate phase margin under varying load conditions.
2Measurement precision
If output resistance is increased to achieve high gain, then DC regulation is improved, but phase margin decreases
Solution Approach 1:
The function of high output resistance is segregated to only the high-gain amplifier path where it is needed for DC regulation, while the low-gain amplifier path maintains lower output resistance to preserve phase margin and transient response. This functional segmentation resolves the contradiction between achieving high gain through increased output resistance and maintaining adequate phase margin.
3Measurement precision
If phase margin is sacrificed to achieve high gain, then DC regulation error is reduced, but transient stability worsens
Solution Approach 1:
The regulator separates DC regulation function (handled by high-gain amplifier) from transient stability function (handled by low-gain amplifier with adequate phase margin). This segmentation allows DC regulation error to be minimized without compromising transient stability, as each aspect is managed by a dedicated amplifier optimized for that purpose.
Solution Approach 2:
The system uses feedback control logic to determine when to switch between the high-gain and low-gain amplifiers based on transient conditions. During transient events, the feedback mechanism activates the low-gain amplifier with adequate phase margin to ensure stability, while during steady-state operation, the high-gain amplifier provides superior DC regulation.
Data Source
AI summary
A voltage regulator that includes a first amplifier, a second amplifier, a summer, and a transistor is presented. The first amplifier has a first gain and a first frequency bandwidth, and is configured to generate a first voltage output. The second amplifier has a second gain that is lower than the first gain and a second frequency bandwidth that is higher than the first frequency bandwidth, and is configured to generate a second voltage output. The summer is configured to generate a summed voltage output. The transistor is connected to the summer and configured to generate a regulated voltage based on the summed voltage output of the summer.