LDO Voltage Regulator Adaptive Pole Tracking
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Solution Overview
Problem
Designing linear voltage regulators that meet stringent and often conflicting requirements such as low power consumption, wide output current and input voltage range, low dropout voltage, and small footprint is challenging, particularly in stabilizing the regulated voltage under varying load conditions.
Innovation Solution
The implementation of a low dropout voltage regulator (LDO) with a tracking circuit that adjusts the zero of the transfer function to track movements of the load pole, using a variable resistor in series with the equivalent series resistance of the load capacitance, and a voltage tracking circuit that replicates the gate-source voltage variations across transistors to maintain stability without increasing the output capacitor size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a small output capacitor is used to minimize PCB footprint, then the device footprint is reduced, but the voltage regulator becomes difficult to stabilize under varying load conditions
Solution Approach 1:
The patent implements a dynamic compensation capacitor that changes its capacitance value based on the load current. When load current is high, the compensation capacitance is increased to ensure stability; when load current is low, the capacitance is reduced to minimize PCB footprint requirements. This dynamic adaptation resolves the contradiction between small footprint and stability under varying loads.
Solution Approach 2:
The patent changes the compensation capacitance parameter dynamically according to load conditions. By adjusting the capacitance value based on load current thresholds, the system optimizes both the PCB footprint (by using small capacitance at low loads) and voltage regulation stability (by using larger capacitance at high loads where it's most needed).
2Stability of the object's composition
If a large output capacitor is used to ensure stability under varying load conditions, then voltage regulation stability is improved, but the PCB footprint increases
Solution Approach 1:
Rather than using a permanently large capacitor, the system dynamically adjusts the compensation capacitance to be large only when needed (under high load conditions) and small when not needed (under low load conditions). This eliminates the need for a permanently large capacitor on the PCB, reducing footprint while maintaining stability when required.
Solution Approach 2:
The compensation capacitance parameter is changed dynamically based on load current measurements. The system switches between different capacitance values to match operational requirements, avoiding the need for a large fixed capacitor and thereby reducing PCB footprint while ensuring stability during high-load operation.
3Stability of the object's composition
If the compensation capacitance is increased to stabilize the regulator under high load current, then voltage regulation stability is improved, but power consumption increases
Solution Approach 1:
The system periodically monitors the load current and adjusts the compensation capacitance accordingly. The capacitance is increased only during periods of high load current when stability is critical, and reduced during periods of low load current when less capacitance is needed. This periodic adjustment minimizes average power consumption while maintaining stability when required.
Solution Approach 2:
The compensation capacitance parameter is dynamically changed based on load conditions. By using larger capacitance only when load current exceeds a threshold and smaller capacitance otherwise, the system reduces the average energy consumption associated with the compensation network while ensuring stability during high-load operation.
4Use of energy by moving object
If the compensation capacitance is decreased to reduce power consumption, then power consumption is reduced, but voltage regulation stability deteriorates under varying load conditions
Solution Approach 1:
The system dynamically adjusts the compensation capacitance to be small during low-load periods (reducing power consumption) and large during high-load periods (maintaining stability). This dynamic behavior resolves the contradiction by ensuring capacitance is large only when both stability is needed and the power consumption penalty is justified by the operational requirements.
Solution Approach 2:
The compensation capacitance parameter is adjusted dynamically based on load current thresholds. The system uses small capacitance values during low-load operation to minimize power consumption and switches to larger capacitance values during high-load operation to maintain voltage regulation stability, optimizing the trade-off between power consumption and stability.
Data Source
AI summary
Devices and methods to design voltage regulators requiring lower power consumption, wide output current and input voltage range, low dropout, and small footprint. The disclosed methods and devices provide solutions to stabilize such regulators in the presence of widely varying loads by tracking a pole of the transfer function, the pole of the transfer function corresponding to a combination of the load capacitance and the load resistance.