Linear Regulator Feedback Loop for Fast Transient Response
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Solution Overview
Problem
Existing linear regulator circuits require high power consumption and complex design due to the need for full-scale error amplifier circuits and independent DC and AC loops, leading to stability conflicts and inefficiencies.
Innovation Solution
A linear regulator circuit with a pre-stage amplifier circuit that includes a current source, differential input circuit, and current mirror circuits forming a positive potential feedback loop, coupled with feedback capacitors to accelerate transient response, allowing the DC and AC loops to feed back to the same node for simplified compensation and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a full-scale error amplifier circuit and multiple current mirror circuits are used to form independent DC and AC loops, then the transient response is accelerated, but the power consumption increases significantly
Solution Approach 1:
The patent merges the DC loop and AC loop into a unified feedback structure where both loops share the same error amplifier circuit and feedback path. The feedback capacitor is integrated into the same node where the DC feedback is applied, eliminating the need for separate AC loop components. This consolidation maintains fast transient response while significantly reducing power consumption by avoiding redundant full-scale amplifier circuits and multiple current mirror circuits.
2Speed
If independent DC loop and AC loop are used to control the power transistor, then the transient response is improved, but the circuit complexity and design difficulty increase
Solution Approach 1:
The patent combines the DC feedback path and AC feedback path into a single unified feedback structure. Both the DC feedback signal and the AC acceleration signal are applied to the same input node of the error amplifier circuit through the feedback capacitor. This merging eliminates the need for separate AC loop components and simplifies the overall circuit architecture while maintaining fast transient response characteristics.
Solution Approach 2:
The error amplifier circuit serves dual functions: it processes both the DC feedback signal for steady-state regulation and the AC feedback signal for transient response acceleration. The feedback capacitor simultaneously provides DC feedback coupling and AC signal acceleration. This multi-functionality reduces the number of dedicated components needed and simplifies the overall circuit design.
3Speed
If independent DC loop and AC loop both control the power transistor, then the transient response is accelerated, but stability conflicts arise between the two loops
Solution Approach 1:
By merging the DC loop and AC loop into a unified feedback structure with a single feedback capacitor, the patent eliminates the stability conflicts that arise from independent loops both controlling the power transistor. The unified structure ensures coordinated operation of DC regulation and AC acceleration functions, maintaining circuit stability while achieving fast transient response.
Data Source
AI summary
A linear regulator circuit having fast transient response includes an error amplifier (EA) circuit and an output stage circuit. The EA circuit amplifies a difference between a feedback signal and a reference signal to generate an error amplified signal. The output stage circuit includes at least one output power switch which is controlled by the error amplified signal to generate an output signal at an output node. The EA circuit includes at least one pre-stage amplifier circuit which includes a current source circuit, a differential input circuit, a first, a second and a third current mirror circuits and at least one feedback capacitor. One differential transistor of the differential input circuit, the first and the second current mirror circuit form a positive potential feedback (PPFB) loop. The feedback capacitor is coupled between the output node and at least one inverting node at the PPFB loop.