Regulator Circuit Phase Compensation for Higher PSRR
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Solution Overview
Problem
Conventional semiconductor regulator circuits face challenges in effectively controlling current and suppressing ripple components, leading to unbalanced load and phase shifts in frequency bands, which affect the Power Supply Rejection Ratio (PSRR) and stability of output voltage.
Innovation Solution
Incorporating a filter with phase variable elements, such as capacitors or inductors, connected between the control node of a differential amplifier and the output transistor, to adjust the phase and frequency response, thereby reducing phase and amplitude differences between the voltage applied to the source and gate electrodes of the output transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional regulator circuit is used, then the circuit structure is simple, but the PSRR is poor due to unbalanced load and phase shifts
Solution Approach 1:
A capacitor is introduced as an intermediary element connected between the control node and output node. This capacitor mediates the signal transmission by providing a frequency-dependent impedance path that balances the load between differential amplifier nodes, thereby reducing phase shifts and improving PSRR without requiring fundamental circuit restructuring
Solution Approach 2:
The invention changes the electrical parameters of the circuit by introducing a capacitor with specific capacitance value. This parameter change modifies the frequency response characteristics and impedance balance of the circuit, enabling phase correction and improved PSRR performance across different frequency bands
2Stability of the object's composition
If no filter is added, then the circuit area is small, but phase shifts and amplitude variations occur affecting output stability
Solution Approach 1:
The capacitor serves multiple functions simultaneously: it acts as a load balancing element, a phase compensation component, and a frequency response modifier. By making this single element multi-functional, the circuit achieves improved output stability without adding separate filter circuits that would increase area
Solution Approach 2:
The capacitor functions as an intermediary that indirectly controls output stability by adjusting the phase and amplitude relationships within the feedback loop, rather than directly filtering the output voltage. This indirect approach achieves stability improvement with minimal circuit area
Data Source
AI summary
A regulator circuit according to one embodiment includes a first transistor, a filter, and a differential amplifier. The first transistor is provided between an input terminal on a power supply side and an output terminal on an output side. The differential amplifier includes an output node connected to the first transistor, and controls the first transistor on the basis of a result of comparison between a reference voltage and a feedback voltage according to an output voltage applied to the output terminal. The filter is connected to a control node that makes a differential pair with the output node, in the differential amplifier.