Programmable LDO Circuit With Overshoot Control for Fast Wake-Up
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Solution Overview
Problem
Existing equipment front-end modules (eFEMs) require specific specifications for module controllers, including ultra-low off-state current, fast wake-up times, and on-die electronic fuse (eFuse) trimming functions, which current low-dropout (LDO) voltage regulators struggle to meet effectively.
Innovation Solution
A programmable output low-dropout (LDO) voltage regulation circuit is designed, incorporating an overshoot control module and coupling circuitry to manage power supply ramping and phase margin optimization, thereby supporting ultra-low leakage current digital cores, on-die eFuse operations, and efficient active mode operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional LDO voltage regulators are used, then basic voltage regulation is achieved, but ultra-low off-state current requirement cannot be met
Solution Approach 1:
The LDO regulator employs dynamic control of the pass transistor channel resistance through the overshoot control module. The channel resistance is increased in response to decreased supply voltage and decreased in response to increased supply voltage, enabling the system to adapt to varying supply conditions while maintaining ultra-low off-state current and stable voltage regulation performance simultaneously
Solution Approach 2:
The overshoot control module monitors supply voltage changes and provides feedback control by adjusting the pass transistor's channel resistance. This feedback mechanism allows the regulator to respond to supply voltage variations, maintaining regulation performance while achieving ultra-low off-state current through optimized transistor operation
2Loss of time
If conventional LDO voltage regulators are used, then basic regulation function is provided, but fast wake-up time cannot be achieved
Solution Approach 1:
The overshoot control module is pre-configured with circuit elements (resistors and transistors) that enable rapid response to supply voltage changes. When the supply voltage increases, the module quickly decreases the pass transistor's channel resistance, reducing wake-up time without requiring complex external circuitry
Solution Approach 2:
The overshoot control module is integrated within the LDO regulator structure, with the control transistor and resistors nested within the existing regulation circuit. This nested configuration achieves fast wake-up functionality while minimizing additional device complexity by reusing existing circuit nodes and components
3Speed
If power supply ramping occurs, then voltage transition is achieved, but overshoot and instability occur
Solution Approach 1:
The overshoot control module anticipates potential overshoot during power supply ramping by monitoring supply voltage changes. When supply voltage increases, the module proactively decreases the pass transistor's channel resistance to counteract the tendency toward output voltage overshoot, maintaining stability during rapid transitions
Solution Approach 2:
The control module continuously monitors supply voltage conditions and provides real-time feedback adjustment of the pass transistor resistance. This feedback control suppresses oscillations and prevents overshoot during power supply ramping, enabling fast voltage transitions while maintaining output stability
4Measurement precision
If phase margin is optimized for stability, then regulation accuracy improves, but response speed decreases
Solution Approach 1:
The system dynamically adjusts the pass transistor's channel resistance based on supply voltage conditions. During transient events, the resistance decreases rapidly to improve response speed, while during steady-state operation, the resistance is optimized for precise voltage regulation, achieving both fast response and high accuracy
Solution Approach 2:
The overshoot control module changes the effective resistance parameter of the pass transistor based on operating conditions. By varying the channel resistance in response to supply voltage changes, the system optimizes the trade-off between phase margin (for accuracy) and response speed, achieving both regulation precision and fast response
Data Source
AI summary
A low-dropout (LDO) voltage regulation circuit comprises a first supply voltage, a first transistor, an overshoot control module, and coupling circuitry configured to couple the first supply voltage, the transistor, and the overshoot control module at a first node.