Linear Power Supply Current Amplification for Load Regulation
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Solution Overview
Problem
In low-power-consumption linear power supply circuits, increasing the gain is challenging when the output capacitor has a small capacity or when the load is heavy, leading to deteriorated load regulation characteristics.
Innovation Solution
The linear power supply circuit includes an error amplifier, a first transistor controlled by the error signal, a current mirror circuit, a bias current source, a current amplifier, and a compensator that compensates for the bias current by a current corresponding to the current outputted from the current amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the output capacitor has a small capacity or the load is heavy, then power consumption is reduced, but the gain cannot be increased and load regulation characteristics deteriorate
Solution Approach 1:
The patent divides the bias current supply into separate paths: one for the error amplifier and another for the output stage through the current mirror circuit. This segmentation allows independent optimization of each stage's current requirements, enabling low overall power consumption while maintaining sufficient gain for good load regulation characteristics.
Solution Approach 2:
The patent changes the current parameter distribution by introducing a current mirror circuit that replicates and scales the bias current. The current amplifier then adjusts the magnitude of the mirrored current to provide adequate drive current to the output stage, achieving both low power consumption and high gain for improved load regulation.
2Stability of the object's composition
If a bias current is supplied to the first transistor and current mirror circuit, then the circuit operates stably, but power consumption increases
Solution Approach 1:
The patent applies partial action by providing bias current only where necessary for stable operation. The current mirror circuit is configured to supply bias current selectively to the output stage without unnecessarily increasing the bias current to the error amplifier, achieving stability with minimal power consumption.
Solution Approach 2:
The current mirror circuit creates a copy of the reference bias current and scales it appropriately for the output stage. This copying mechanism ensures stable operation with predictable current distribution while avoiding excessive power consumption by using the same reference current source for multiple stages.
3Reliability
If the gain is increased to improve load regulation characteristics, then the load regulation characteristics improve, but power consumption increases
Solution Approach 1:
The patent introduces dynamic current amplification through the current amplifier stage that can adjust its gain based on operating conditions. The current mirror circuit dynamically replicates and scales currents to provide high gain when needed for load regulation while consuming minimal power during normal operation.
Solution Approach 2:
The current mirror circuit acts as an intermediary between the low-power bias current source and the high-current output stage. It provides current amplification and isolation, enabling high gain for improved load regulation characteristics without requiring excessive bias current and thus avoiding increased power consumption.
Data Source
AI summary
A linear power supply circuit includes: an error amplifier configured to output an error signal according to a difference between a feedback voltage based on an output voltage and a reference voltage; a first transistor configured to be controlled by the error signal; a current mirror circuit; a bias current source configured to distribute and supply a bias current to the first transistor and the current mirror circuit; a current amplifier configured to amplify a current outputted from the current mirror circuit; and a compensator configured to compensate for the bias current by a current corresponding to the current outputted from the current amplifier.