Regulator Circuit Parallel Transistors Load Stability
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Solution Overview
Problem
Conventional linear regulators face challenges in maintaining stability over a wide load range, leading to reduced phase and gain margins, and transient characteristics degradation due to the need for trade-offs in responsivity, and existing solutions like parallel coupling of regulators with delayed error amplifier activation result in oscillations and voltage fluctuations.
Innovation Solution
A regulator circuit with parallel transistors and error amplifiers, where the first error amplifier remains operational in light-load states and seamlessly switches to the second error amplifier in heavy-load states, maintaining stability and reducing power consumption by dynamically adjusting target voltages and feedback ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single error amplifier is used to control the output transistor, then the circuit structure is simple, but stability is reduced over wide load ranges due to reduced phase margin and gain margin
Solution Approach 1:
The patent divides the error amplification function into two separate error amplifiers (first error amplifier for light-load, second error amplifier for heavy-load) that operate in different load ranges. This segmentation allows each amplifier to be optimized for its specific load condition, maintaining stability across the entire load range while avoiding the trade-off between circuit simplicity and stability.
2Reliability
If multiple linear regulators are coupled in parallel with switching between error amplifiers, then stability over wide load range is improved, but power consumption increases and oscillation may occur due to delayed error amplifier activation
Solution Approach 1:
The patent implements dynamic switching between the first and second error amplifiers based on load conditions. The switching mechanism activates the appropriate error amplifier according to whether the load is light or heavy, ensuring optimal performance while minimizing power consumption by keeping only the necessary amplifier active at any given time.
Solution Approach 2:
The patent maintains both error amplifiers in a ready state with appropriate biasing, allowing for immediate activation without delay when load conditions change. This preliminary preparation prevents oscillation by ensuring the active error amplifier responds instantly to load transitions, eliminating the delay problem associated with activating error amplifiers from an off state.
3Use of energy by moving object
If error amplifier is completely turned off in light-load state to reduce power consumption, then power consumption is reduced, but transient characteristics degrade due to delay in responsivity when switching to heavy-load state
Solution Approach 1:
The patent applies different operational states to different error amplifiers based on local load conditions. The first error amplifier remains active during light-load states while the second is inactive, and vice versa during heavy-load states. This localized quality approach ensures that the active error amplifier always has immediate responsivity to load changes in its designated operating range, eliminating transient degradation while maintaining power efficiency.
Data Source
AI summary
A regulator circuit supplies an output voltage VOUT to a load. A second transistor is arranged in parallel with a first transistor, and has a relatively small size. A feedback circuit generates a first feedback signal and a second feedback signal according to the output voltage VOUT. A first error amplifier controls the first transistor such that the first feedback signal approaches a first reference value. A second error amplifier controls the second transistor such that the second feedback signal approaches a second reference value. In a light-load state, the operation of the first error amplifier is maintained.