Voltage Regulator Transient Response via Third Amplifier
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Solution Overview
Problem
Conventional voltage regulators with a three-stage amplifier circuit configuration suffer from phase delay and instability due to the charging and discharging of parasitic capacitance, leading to undershoot or overshoot in output voltage during load transient responses.
Innovation Solution
A voltage regulator design that includes a third source ground amplifier circuit between the differential amplifier circuit and the second source ground amplifier circuit, allowing direct control of the output MOS transistor's gate without a resistor, thereby improving transient response characteristics and maintaining stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a voltage three-stage amplifier circuit configuration is used, then transient response characteristics are improved, but phase delay occurs causing unstable operation
Solution Approach 1:
A third source ground amplifier circuit is introduced as an intermediary between the differential amplifier circuit and the second source ground amplifier circuit. This intermediate stage helps manage the phase delay by providing an additional control point, allowing the system to maintain stability while preserving the wide frequency band needed for good transient response characteristics.
2Stability of the object's composition
If resistor 121 and capacitor 122 are added for phase compensation, then stable operation is maintained, but delay in charging and discharging parasitic capacitance occurs
Solution Approach 1:
The amplifier circuit is segmented into three distinct source ground amplifier stages, with the third stage specifically dedicated to controlling the gate of the output MOS transistor. This segmentation allows the phase compensation function to be separated from the direct gate control path, enabling stable operation through RC compensation while the third stage provides timely gate voltage control to reduce charging/discharging delays.
3Speed
If the output of the third source ground amplifier circuit is connected directly to the gate of the output MOS transistor, then transient response is improved, but control complexity increases
Solution Approach 1:
The third source ground amplifier circuit serves multiple functions: it directly controls the gate voltage of the output MOS transistor for fast transient response, while also working in conjunction with the phase compensation circuit (resistor 121 and capacitor 122) to maintain stability. This multi-functionality allows the additional circuit element to justify its presence by delivering both speed and stability improvements.
Data Source
AI summary
A voltage regulator having good transient response characteristics and maintaining stable operation is provided. The voltage regulator includes: a first MOS transistor having a gate terminal connected to an output terminal of the differential amplifier circuit; a first constant current source provided between the first MOS transistor and a ground terminal; an output MOS transistor having a gate terminal connected to a drain terminal of the first MOS transistor via a phase compensation circuit; a second MOS transistor having a gate terminal to which an output of the differential amplifier circuit is input and a drain terminal connected to the gate terminal of the output MOS transistor; and a second constant current source provided between the second MOS transistor and a ground terminal.