Fast Transient Linear Regulator Using Miller Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Linear regulator circuits, particularly low dropout (LDO) regulator circuits, face challenges in balancing quiescent current, transient response, and occupied area, with existing designs often experiencing slow transient performance due to limitations in error amplifier and compensation mechanisms.
Innovation Solution
The proposed linear regulator circuit incorporates a pass element, an error amplifier with a current mirror stage, a buffer, and a miller compensation circuit, along with a feed-forward loading stage to enhance transient response by adjusting loading currents and reducing output impedance, thereby stabilizing output voltage quickly during transient events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional error amplifier and compensation mechanisms are used in LDO regulator circuits, then circuit simplicity is maintained, but transient response performance deteriorates (slow transient response)
Solution Approach 1:
The error amplifier is divided into two independent stages: a first stage that generates a first current signal and a second stage that generates a second current signal. This segmentation allows each stage to be optimized for specific functions, with the first stage handling reference voltage comparison and the second stage handling feedback voltage comparison, thereby improving transient response without excessive complexity
Solution Approach 2:
The miller compensation circuit is configured to control the first current signal in advance before transient events occur. By pre-configuring the compensation circuit to actively control the first current signal, the system prepares for potential transients, enabling faster response when transients actually occur without requiring complex reactive compensation networks
2Stability of the object's composition
If larger compensation circuits are used to improve stability, then output voltage stability improves, but occupied area increases
Solution Approach 1:
The miller compensation circuit acts as an intermediary between the error amplifier and the output, using a compact capacitor-based structure to provide phase compensation and stabilize output voltage. This intermediary approach achieves voltage stability without requiring large-area traditional compensation circuits, as the miller effect allows small capacitors to achieve equivalent compensation of larger values
3Speed
If traditional LDO regulator design is used, then quiescent current is kept low, but transient response performance deteriorates
Solution Approach 1:
The error amplifier uses dynamic current signaling where the first and second current signals can rapidly change in magnitude and direction based on transient conditions. The differential pair and current mirror configuration allow the circuit to dynamically adjust current levels during transients while maintaining low quiescent current when the circuit is in steady state, achieving fast response without continuous high power consumption
Data Source
AI summary
A linear regulator includes a pass element, an error amplifier, and a miller compensation circuit. The error amplifier is configured to provide an error signal to the control terminal of the pass element in response to a reference voltage and a feedback voltage. The error amplifier includes a current mirror stage and a first stage. The current mirror stage is configured to receive the input voltage. The first stage is configured to provide a first current signal to a first terminal of the current mirror stage in response to the reference voltage, and provide a second current signal to a second terminal of the current mirror stage in response to the feedback voltage. The miller compensation circuit is coupled between the second terminal of the pass element and the error amplifier. The miller compensation circuit is configured to control the first current signal.