Dual-Loop LDO Regulation for Fast Transient Response
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Solution Overview
Problem
Conventional LDO designs struggle with transient response and settle time, particularly in high-speed applications, due to voltage undershoot or overshoot from rapid load current changes, and the limitations of output capacitors.
Innovation Solution
A dual-loop LDO architecture with a large-geometry primary LDO regulator and a small-geometry secondary LDO regulator, combined with a signal coupling circuit, enhances transient response and minimizes settle time without external capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional LDO design uses a single regulator with traditional output capacitor, then the circuit is simple and stable, but the transient response is slow and settle time is excessive for high-speed interfaces
Solution Approach 1:
The patent divides the single LDO regulator into two parallel regulators: a first LDO regulator with large-geometry differential amplifier for robust current driving, and a second LDO regulator with small-geometry differential amplifier for rapid response. This segmentation allows each regulator to specialize in different aspects of voltage regulation, achieving both fast transient response and stable operation without requiring large output capacitors.
Solution Approach 2:
The patent implements dynamic switching between two LDO regulators based on load conditions. The control circuit dynamically selects which regulator to activate - using the first regulator for heavy load conditions requiring high current drive, and the second regulator for light load conditions requiring fast response. This dynamic adaptation optimizes both transient response speed and settle time across varying operating conditions.
2Stability of the object's composition
If large output capacitors are used to stabilize LDO output, then voltage stability is improved, but space is consumed and response time increases
Solution Approach 1:
The patent segments the voltage stabilization function between two parallel LDO regulators, each with optimized characteristics. The first regulator provides robust stabilization through large-geometry differential amplifier for high current applications, while the second regulator provides fast stabilization through small-geometry differential amplifier for low current applications. This eliminates the need for large output capacitors that would otherwise be required to achieve both stability and fast response.
Solution Approach 2:
The patent changes the geometric parameters of the differential amplifiers in the two regulators - using large geometry in the first regulator for high current drive capability and stable operation, and small geometry in the second regulator for fast response and minimal settle time. This parameter differentiation allows the system to achieve voltage stability without relying on large output capacitors, thereby reducing both space consumption and settle time.
3Power
If a single LDO regulator is used, then the device complexity is low, but the current driving capability and response speed cannot simultaneously satisfy high-speed interface requirements
Solution Approach 1:
The patent segments the current driving function between two parallel regulators with different differential amplifier geometries. The first regulator with large-geometry differential amplifier handles high current demands for robust power delivery, while the second regulator with small-geometry differential amplifier handles low current demands for fast response. This segmentation enables simultaneous satisfaction of both high current driving capability and fast response requirements, which cannot be achieved with a single regulator.
Solution Approach 2:
The patent creates a multi-functional regulator system where two LDO regulators work in parallel to provide both high current driving capability and fast transient response. The control circuit universally manages both regulators, selecting the appropriate one based on load conditions. This universal approach allows the system to adapt to varying power and speed requirements, achieving multi-functionality that satisfies high-speed interface requirements while maintaining reasonable device complexity through systematic design.
Data Source
AI summary
A voltage regulation device includes: a first low-dropout (LDO) regulator, a second LDO regulator and a signal coupling circuit. The first LDO regulator is configured to receive an input voltage of the voltage regulation device and accordingly generate and stabilize an output voltage of the voltage regulation device. The second LDO regulator is coupled in parallel with the first LDO regulator, and configured to provide supplementary regulation to further stabilize the output voltage. The signal coupling circuit is coupled between the first LDO regulator and the second LDO regulator, configured to apply a voltage provided by second LDO regulator to the first LDO regulator, thereby modulating an operation of the first LDO regulator.