Regulator Circuit Clamp Control for Voltage Stability
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Solution Overview
Problem
Regulator circuits face challenges in maintaining stable output voltage due to fluctuations in input voltage and output current, leading to overshooting or undershooting, and existing solutions either increase power consumption or struggle to suppress voltage fluctuations effectively.
Innovation Solution
A regulator circuit design incorporating a fluctuation detection capacitor, current feedback circuit, and clamp circuit that adjusts the gate-source voltage of the output transistor to suppress overshooting and undershooting, while maintaining stable output voltage without significant power consumption increases, by using a P-channel MOSFET and a clamp circuit that sets upper and lower limits for the gate-source voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the transistor size is increased to provide large current capacity, then the current capacity is improved, but the gate capacitance increases leading to response delay
Solution Approach 1:
The clamp circuit performs preliminary action by pre-charging or pre-discharging the gate capacitance of the output transistor before the error amplifier needs to make adjustments. This allows the transistor to respond more quickly to load changes without requiring a larger transistor size, thereby maintaining both current capacity and response speed.
Solution Approach 2:
The clamp circuit acts as an intermediary between the error amplifier and the output transistor. It provides an additional current path that supplements the error amplifier's control current, enabling faster response without increasing the transistor size. The clamp circuit mediates the control signal to accelerate the transistor's response to load transients.
2Speed
If the bias current of the error amplifier is increased to increase response speed, then the response speed is improved, but the power consumption increases
Solution Approach 1:
The clamp circuit provides periodic or transient current bursts to the gate of the output transistor during load transients, rather than requiring a continuously high bias current. This allows the error amplifier to maintain low power consumption during steady-state operation while still achieving fast response when needed, through periodic current supplementation from the clamp circuit.
Solution Approach 2:
The clamp circuit dynamically adjusts its current contribution based on the operating conditions. During load transients, it provides additional current to accelerate response; during steady-state operation, it remains inactive or provides minimal current. This dynamic behavior enables fast response speed without requiring continuously high power consumption from the error amplifier.
3Use of energy by moving object
If the bias current is reduced to decrease power consumption, then the power consumption is improved, but the response speed is reduced leading to voltage fluctuation
Solution Approach 1:
The clamp circuit serves as an intermediary current source that supplements the error amplifier's output during transient conditions. It provides additional current to the gate of the output transistor when load changes occur, ensuring fast response and voltage stability even when the error amplifier operates with low bias current for power efficiency. This intermediary support maintains reliability without sacrificing power consumption.
Solution Approach 2:
The clamp circuit detects load current changes and provides preliminary current action to the output transistor gate before the error amplifier can respond with its low bias current. This preliminary action prevents voltage fluctuations during transients, maintaining output voltage stability (reliability) while allowing the error amplifier to operate at low power consumption levels during steady-state operation.
4Power
If the transistor size is increased to provide large current capacity, then the current capacity is improved, but the gate capacitance increases leading to overshooting or undershooting
Solution Approach 1:
The clamp circuit performs preliminary charging or discharging of the gate capacitance in anticipation of or concurrent with load changes. This preliminary action reduces the voltage swing required from the error amplifier, minimizing overshooting or undershooting of the output voltage. The output transistor can maintain large current capacity with appropriate sizing while the clamp circuit's preliminary action prevents excessive voltage excursions.
Solution Approach 2:
The clamp circuit acts as an intermediary that provides current support during transient conditions, reducing the burden on the error amplifier to rapidly charge/discharge the gate capacitance. This mediation smooths the gate voltage transition, preventing overshooting or undershooting of the output voltage while allowing the transistor to be sized for large current capacity without compromising stability.
Data Source
AI summary
An output transistor is provided between an input terminal and an output terminal. An error amplifier adjusts the gate voltage of the output transistor such that the voltage that corresponds to the output voltage approaches a predetermined reference voltage. A fluctuation detection capacitor is provided on a path from the input terminal to a grounded terminal, which sets one terminal thereof to a fixed voltage. A current feedback circuit supplies, to the gate of the output transistor, the current that corresponds to the current that flows through the fluctuation detection capacitor. A clamp circuit clamps the gate voltage of the output transistor. The clamp circuit 30 clamps the gate voltage of the output transistor such that the voltage difference between the gate of the output transistor and the input terminal exhibits a predetermined clamp voltage or more.