Adaptive Gain Control for Voltage Regulator Stability
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Solution Overview
Problem
Voltage regulators face challenges in reducing internal losses and dropout voltages, which affect their efficiency and stability, especially when dealing with varying input voltages and load currents.
Innovation Solution
A voltage regulator with an adjustable gain output amplification stage, utilizing a current mirror formed by a pass transistor and a drive transistor, where the gain is controlled by a gain control circuit based on output current, input voltage, and output voltage differences to minimize internal losses and maintain stability, even at small dropout voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the gain of the output amplification stage is increased to reduce internal losses, then power efficiency improves, but stability and transient response may deteriorate
Solution Approach 1:
The patent applies dynamics by making the gain of the output amplification stage adjustable rather than fixed. The gain control circuit dynamically adjusts the mirror ratio of the current mirror based on operating conditions (output current, input voltage, output voltage), allowing the system to optimize between power efficiency and stability for different load conditions. This resolves the contradiction by enabling high gain when needed for efficiency while maintaining stability through adaptive control.
Solution Approach 2:
The patent changes the parameter of gain (through adjustable mirror ratio) based on operating conditions. The gain control circuit modifies the effective gain of the output amplification stage by adjusting the current mirror ratio in response to changes in output current, input voltage, and output voltage. This parameter adaptation allows the system to achieve reduced internal losses while maintaining stability across varying operating conditions.
2Loss of energy
If the gain is adjusted to reduce dropout voltage, then voltage regulation efficiency improves, but device complexity increases
Solution Approach 1:
The gain control circuit performs multiple functions: it adjusts the mirror ratio to optimize gain, senses output current, and responds to input/output voltage variations. By consolidating these control functions into a single circuit block that leverages existing circuit elements, the patent achieves reduced dropout voltage without proportionally increasing overall device complexity. The current mirror structure itself serves both as the amplification mechanism and as the basis for gain adjustment.
Solution Approach 2:
The gain control circuit utilizes the existing current mirror structure and operating conditions (output current, input voltage, output voltage) to automatically adjust the gain. The circuit self-regulates the mirror ratio based on feedback from the operating conditions, eliminating the need for external complex control mechanisms. This self-service approach reduces dropout voltage while keeping the added complexity minimal.
3Loss of energy
If a fixed high gain is used to minimize internal losses, then power efficiency improves, but adaptability to varying load conditions deteriorates
Solution Approach 1:
The patent makes the gain dynamic rather than fixed by implementing an adjustable current mirror ratio controlled by the gain control circuit. The mirror ratio is adjusted in response to varying output current, input voltage, and output voltage conditions, allowing the system to maintain optimal power efficiency across different load conditions. This dynamic adaptation resolves the contradiction between achieving low internal losses and maintaining versatility.
Solution Approach 2:
The gain control circuit implements feedback by sensing the output current and responding to input/output voltage variations to adjust the mirror ratio accordingly. This feedback mechanism ensures that the gain is optimized for current operating conditions, allowing the system to minimize internal losses while adapting to varying load conditions. The feedback loop continuously adjusts the gain to maintain optimal efficiency across the full range of operating conditions.
Data Source
AI summary
A voltage regulator which provides an output current at an output voltage at an output node, based on an input voltage at an input node is described. The voltage regulator has an output amplification stage comprising a pass transistor for deriving the output current at the output node from the input voltage at the input node; and comprising a driver stage to set a gate voltage at a gate of the pass transistor based on a drive voltage. A gain of the output amplification stage is adjustable. Furthermore, the voltage regulator comprises a differential amplification unit to determine the drive voltage in dependence of the output voltage and in dependence of a reference voltage. In addition, the voltage regulator comprises a gain control circuit to adjust the gain of the output amplification stage in dependence of the output current.