Two-Stage LDO Power Supply Stability via Segmented Amplifiers
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Solution Overview
Problem
Existing low-dropout (LDO) linear power supply systems face challenges in ensuring stability and efficiency over a wide range of load and output capacitance values, often resulting in a narrow 'Tunnel of Death' stability region and compromised robustness due to conflicting requirements of output voltage filtering and frequency compensation.
Innovation Solution
A two-stage LDO linear power supply system is implemented, featuring a pass-element, a compensation amplifier stage for frequency compensation, and a gain amplifier stage for DC gain scaling, with a capacitor and equivalent series resistor (ESR) for output filtering, decoupling the functions of filtering and compensation to enhance stability and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage LDO linear power supply is used, then the device complexity is low, but the stability region is narrow and robustness is compromised
Solution Approach 1:
The power supply system is divided into two independent amplifier stages: a compensation amplifier stage for frequency compensation and a gain amplifier stage for DC gain scaling. This segmentation allows each stage to independently optimize its function, expanding the stability region while maintaining manageable complexity through modular design.
2Device complexity
If output voltage filtering and frequency compensation are combined in a single stage, then the device complexity is low, but the stability over wide range of component values is compromised
Solution Approach 1:
The filtering function (handled by output capacitor and ESR) and frequency compensation function (handled by compensation amplifier stage) are separated into independent functional blocks. This allows the system to maintain stability over wide ranges of component values while keeping the overall device complexity manageable through functional modularity.
3Device complexity
If DC gain scaling is not provided, then the device complexity is low, but the adaptability to different input voltage ranges is limited
Solution Approach 1:
The gain amplifier stage provides dynamically adjustable DC gain scaling that adapts to different input voltage ranges. This dynamic gain adjustment capability allows the power supply to maintain optimal performance across varying input conditions while adding only moderate complexity through a single additional amplifier stage.
Data Source
AI summary
Aspects of the present invention include a low-dropout (LDO) linear power supply system. The system includes a pass-element configured to generate an output voltage at an output based on an input voltage. The system also includes a compensation amplifier stage coupled to the output and configured to provide frequency compensation and provide a desired frequency response of the output voltage. The system further includes a gain amplifier stage interconnecting the compensation amplifier stage and the pass-element and configured to provide DC gain scaling to generate the output voltage substantially proportional to the input voltage within a given range of the input voltage.