Dual-Loop Voltage Regulator for Gain-Phase Tradeoff
Find Innovative SolutionsGenerate Solutions
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, especially under varying load conditions.
Innovation Solution
A dual loop voltage regulator design utilizing two amplifiers with different gain and frequency bandwidths, where a fast, low-gain amplifier and a slow, high-gain amplifier are used in conjunction to shape the gain and phase, allowing for improved DC regulation, transient stability, and extended frequency bandwidth.
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. Each amplifier operates independently with optimized gain characteristics, allowing the high-gain amplifier to improve DC regulation accuracy without compromising the phase margin of the overall system, as the low-gain amplifier maintains stability during transient conditions.
Solution Approach 2:
The system dynamically switches between different amplifier gain characteristics based on operating conditions. During steady-state DC operation, the high-gain amplifier dominates to provide precise regulation. During transient load changes, the low-gain amplifier with higher bandwidth and better phase margin characteristics takes over, enabling the system to adapt its gain properties to maintain both accuracy and stability.
2Measurement precision
If output resistance is increased to achieve high gain, then DC regulation is improved, but phase margin decreases
Solution Approach 1:
The output resistance function is segmented between two amplifiers. The high-gain amplifier uses increased output resistance to achieve high DC gain for accurate regulation, while the low-gain amplifier compensates for phase margin degradation by providing additional bandwidth and stability during transient responses, effectively separating the functions of high output resistance from phase margin maintenance.
Solution Approach 2:
The system changes the effective output resistance parameter dynamically through the interaction of two amplifiers. The high-gain amplifier provides high output resistance for DC accuracy, while the low-gain amplifier's higher bandwidth compensates for the phase margin reduction caused by high output resistance, allowing the system to maintain both high DC gain and adequate phase margin across different operating conditions.
3Measurement precision
If a single amplifier is used to achieve high gain, then DC regulation is improved, but frequency bandwidth is limited
Solution Approach 1:
The frequency bandwidth is segmented into two ranges handled by different amplifiers. The high-gain amplifier covers low-frequency DC regulation with high accuracy, while the low-gain amplifier extends the high-frequency response with its higher bandwidth capability. This segmentation allows the system to achieve both high DC regulation accuracy and extended frequency bandwidth that a single amplifier cannot provide alone.
Solution Approach 2:
The two amplifiers are merged in a parallel configuration where their transfer functions combine to create an overall system response that exhibits both high DC gain and extended bandwidth. The high-gain amplifier dominates at low frequencies for accurate DC regulation, while the low-gain amplifier dominates at high frequencies, creating a composite frequency response that exceeds what either amplifier could achieve individually.
Data Source
AI summary
A voltage regulator includes a first amplifier having a first gain and a first frequency bandwidth, and generating a first voltage output; a second amplifier having a second gain that is lower than the first gain and a second frequency bandwidth that is higher than the first frequency bandwidth, and generating a second voltage output; a summer generating a summed voltage output based on the first voltage output and the second voltage output; and a transistor connected to the summer and generating a regulated voltage based on the summed voltage output of the summer.