Voltage Regulator Suppressing Overshoot via Fast Gate Discharge
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Solution Overview
Problem
Mobile devices face challenges in maintaining stable output voltage due to limited battery capacity, leading to overshoot and undershoot issues caused by rapid changes in output current, which affect power efficiency and accuracy of low-dropout (LDO) regulators.
Innovation Solution
A voltage regulator design incorporating a diode formed by a transistor connected between the gate and source of a power transistor, coupled with an internal fast loop, which quickly discharges current to suppress overshoot and undershoot by connecting the gate of the power transistor to ground or the output node, ensuring efficient voltage regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dropout voltage is increased to ensure stable voltage regulation, then the reliability of voltage output is improved, but the power efficiency deteriorates
Solution Approach 1:
The patent implements dynamic control of the power transistor's gate voltage through a buffer amplifier and feedback network, allowing the transistor to operate in different regions (linear vs. saturation) based on load conditions. This dynamic operation enables the system to maintain stable voltage regulation when needed while minimizing voltage drop and maximizing power efficiency under varying load conditions.
Solution Approach 2:
The patent employs a feedback network that continuously monitors the output voltage and adjusts the gate voltage of the power transistor accordingly. This closed-loop feedback mechanism ensures that the voltage regulator maintains reliable output voltage while adapting to load changes, thereby optimizing power efficiency without sacrificing regulation stability.
2Stability of the object's composition
If the response speed is increased to suppress overshoot and undershoot, then the stability of output voltage is improved, but the device complexity increases
Solution Approach 1:
The patent incorporates a buffer amplifier that proactively adjusts the gate voltage of the power transistor in anticipation of load changes. By preparing the gate voltage in advance and providing a controlled transition path, the system can quickly respond to overshoot and undershoot conditions without requiring complex control circuits, thus achieving fast response with moderate complexity.
3Measurement precision
If the buffer amplification is increased to improve gate voltage control, then the measurement precision of voltage regulation is improved, but the use of energy increases
Solution Approach 1:
The patent implements a buffer amplifier with gain greater than unity to provide sufficient gate voltage drive for precise control of the power transistor. While this partial over-amplification increases energy consumption in the buffer stage, it enables accurate voltage regulation that prevents larger energy losses in the power transistor, achieving net energy efficiency through precise control.
Data Source
AI summary
A voltage regulator may include an error amplifier configured to amplify a difference between a reference voltage and a feedback voltage and generate a first amplified voltage based thereon; a power transistor between a second voltage supply node and an output node of the voltage regulator, the power transistor including a gate configured to receive a gate voltage; a buffer between a first voltage supply node and a ground, the buffer configured to generate the gate voltage based on the first amplified voltage; a voltage divider between the output node and the ground, the voltage divider configured to generate the feedback voltage based on the output voltage; and a control circuit configured to connect the output node to the ground through the gate of the power transistor based on the output voltage and the gate voltage.