Dual-Loop LDO Circuit for Fast Voltage Stabilization
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Solution Overview
Problem
Conventional low dropout regulator (LDO) circuits face challenges in stabilizing output voltage quickly and efficiently, with limitations in loop gain, noise reduction, quiescent current, and stability.
Innovation Solution
The proposed LDO circuit employs two adjustment pipes and two error amplifiers, forming two loops that are selectively turned on or off to control output voltage, removing sampling circuits and incorporating PMOS and NMOS transistors, along with a load module and bias circuit to enhance stability and transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional LDO circuit with single adjustment pipe and error amplifier is used, then structure is simple and cost is low, but output voltage stabilization speed is slow
Solution Approach 1:
The patent divides the single adjustment pipe into two separate adjustment pipes (first adjustment pipe MP1 and second adjustment pipe MP2), each controlled by its own error amplifier (A1 and A2). This segmentation allows independent control of upper and lower voltage adjustment, enabling faster response and stabilization speed while maintaining reasonable circuit complexity through modular design.
Solution Approach 2:
The patent implements dynamic control by using two error amplifiers that can independently adjust their respective adjustment pipes based on real-time voltage feedback. The error amplifiers dynamically respond to voltage deviations and adjust the adjustment pipes accordingly, enabling fast stabilization without requiring complex external control circuits.
2Reliability
If conventional LDO circuit with sampling resisters is used, then circuit is simple, but loop gain is limited and noise is high
Solution Approach 1:
The patent removes the sampling resisters (R1 and R2) from the conventional LDO circuit and replaces them with direct feedback connections from the output end to the error amplifiers. This extraction eliminates the noise introduced by resister sampling and removes the loop gain limitations imposed by the voltage divider network, while maintaining circuit simplicity.
Solution Approach 2:
The patent creates a parallel structure with two error amplifiers and two adjustment pipes, where each amplifier-pipe pair operates independently. This copying approach provides redundant control paths that improve reliability and noise performance without requiring complex sampling networks.
3Productivity
If conventional LDO circuit with single adjustment pipe is used, then quiescent current is low, but transient response is slow
Solution Approach 1:
The patent segments the single adjustment pipe into two parallel adjustment pipes (MP1 and MP2), each capable of independent operation. During transient conditions, both pipes can actively respond to load changes, doubling the effective response capability and improving transient response speed without requiring a proportional increase in quiescent current.
Solution Approach 2:
The patent merges two error amplifiers and two adjustment pipes into a coordinated system where both components work together during transient events. The combined system provides enhanced transient response capability while maintaining efficient current management through the coordinated operation of the dual amplifiers and pipes.
Data Source
AI summary
The present disclosure relates to semiconductors and low dropout regulator (LDO) circuits. A LDO circuit may include first and second adjustment pipes and first and second error amplifiers. When an output voltage outputted by the output end of the LDO circuit is smaller than a reference voltage, the first error amplifier controls the first adjustment pipe to be turned on, and the second error amplifier controls the second adjustment pipe to be turned off. Alternative, when the output voltage is greater than the reference voltage, the first error amplifier controls the first adjustment pipe to be turned off, and the second error amplifier controls the second adjustment pipe to be turned on.