Low-consumption Voltage Regulator with AB Class Amplifier
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Solution Overview
Problem
ULDO voltage regulators face inefficiencies in response time due to parasitic capacitances, requiring significant current peaks to charge and discharge, which is problematic when load currents are low, leading to reduced benefits in response time.
Innovation Solution
A low-consumption voltage regulator utilizing an AB class amplifier eliminates the need for a voltage buffer, reducing the number of poles to enhance frequency compensation and achieve faster response times by amplifying the difference between a reference voltage and a fraction of the regulated voltage, thereby stabilizing the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage buffer stage is introduced to release parasitic capacitance, then the regulator loop gain is improved, but the device complexity increases due to an additional third pole that complicates compensation
Solution Approach 1:
The patent removes the voltage buffer stage (transistor Q1 and mirror M1-M2) from the regulator circuit, extracting the problematic third pole while maintaining the essential error amplification function through the AB class amplifier configuration. This elimination simplifies the compensation network while preserving loop gain characteristics.
Solution Approach 2:
The patent combines the error amplification and output driving functions into a single AB class amplifier stage, merging what were previously separate functional blocks (error amplifier + buffer stage) into one integrated configuration that drives the power transistor directly without intermediate buffer components.
2Use of energy by moving object
If the load current is low, then the power consumption is reduced, but the response time benefit from current recovery becomes negligible
Solution Approach 1:
The AB class amplifier dynamically adjusts its operating point and current drive capability based on the instantaneous load conditions. Unlike fixed-class amplifiers, it can operate efficiently at low currents while maintaining the ability to deliver high current peaks when needed, adapting its characteristics to match the varying load requirements.
Solution Approach 2:
The patent changes the operational parameters of the amplifier by using AB class operation instead of class A, allowing the bias current and transconductance to vary with signal amplitude and load conditions. This enables the amplifier to maintain high gain at low currents while preserving fast response capability when large current swings are required.
Data Source
AI summary
A voltage regulator having an input voltage and adapted to supply a regulated output voltage, the regulator including an AB class amplifier and a power transistor having a non-drivable terminal coupled to the input voltage, a non-drivable terminal coupled to a reference voltage and a drivable terminal coupled to the output terminal of the amplifier; the amplifier is adapted to amplify the voltage difference between a further reference voltage and a fraction of the regulated voltage.