LDO Voltage Regulator Dynamic Biasing for Fast Load Transients
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low dropout (LDO) voltage regulators face challenges in reducing voltage undershoot caused by changes in load current from a light load to a heavy load, as existing adaptive current biasing methods are insufficient due to initial small loop bandwidth, leading to significant transient response delays and voltage fluctuations.
Innovation Solution
The implementation of dynamic current biasing, which involves a bias current source capacitively coupled to the output of the LDO regulator via a feedback capacitor, allowing for quick detection and response to transient voltage drops by boosting the bias current to the amplifying circuit, thereby reducing undershoot and improving transient response times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If adaptive current biasing is used in LDO regulators, then power consumption is reduced, but transient response time increases and voltage undershoot worsens
Solution Approach 1:
The patent implements dynamic current biasing where the bias current to the amplifying circuit is dynamically adjusted based on load conditions. A capacitor couples the output to the current source, enabling the system to automatically increase bias current during transient load changes and maintain low bias current during steady-state operation, thus resolving the contradiction between power consumption and transient response time
Solution Approach 2:
The patent employs feedback by coupling the output voltage back to the current source through a capacitor. This feedback mechanism detects transient voltage drops and automatically adjusts the bias current accordingly, allowing the system to maintain low power consumption during normal operation while providing fast transient response when needed
2Loss of energy
If adaptive current biasing is used in LDO regulators, then power consumption is reduced, but voltage stability during transient load changes worsens
Solution Approach 1:
The patent implements dynamic current biasing where the bias current to the amplifying circuit is dynamically adjusted based on load conditions. A capacitor couples the output to the current source, enabling the system to automatically increase bias current during transient load changes and maintain low bias current during steady-state operation, thus resolving the contradiction between power consumption and transient response time
Solution Approach 2:
The patent employs feedback by coupling the output voltage back to the current source through a capacitor. This feedback mechanism detects transient voltage drops and automatically adjusts the bias current accordingly, allowing the system to maintain low power consumption during normal operation while providing fast transient response when needed
3Loss of time
If loop bandwidth is increased to improve transient response, then transient response time decreases, but power consumption increases
Solution Approach 1:
The patent implements dynamic current biasing where the bias current to the amplifying circuit is dynamically adjusted based on load conditions. A capacitor couples the output to the current source, enabling the system to automatically increase bias current during transient load changes and maintain low bias current during steady-state operation, thus resolving the contradiction between power consumption and transient response time
Solution Approach 2:
The patent uses periodic action by implementing current biasing that activates only during transient conditions rather than continuously. The capacitor-coupled feedback mechanism enables the system to provide high bandwidth only when transient voltage drops are detected, rather than maintaining high bandwidth continuously, thus reducing overall power consumption while improving transient response when needed
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Dynamic current biasing effectively reduces voltage undershoot and improves the transient response of LDO regulators by quickly increasing the bias current in response to transient voltage drops, addressing the limitations of adaptive current biasing and ensuring more stable output voltages during load changes.
Implementation Method 1
A capacitor may be coupled between a source of the bias current and the output of the LDO regulator. The capacitor may couple a transient voltage drop in the output voltage to a gate of the pass device.
Data Source
AI summary
In certain aspects, a voltage regulator includes a pass device coupled between an input of the voltage regulator and an output of the voltage regulator. The voltage regulator also includes an amplifying circuit having a first input, a second input, and an output, wherein the first input is configured to receive a reference voltage, the second input is coupled to the output of the voltage regulator via a feedback path, and the output of the amplifying circuit is coupled to a gate of the pass device. The voltage regulator further includes a first current source coupled between a supply rail and the amplifying circuit, and a capacitor coupled between the first current source and the output of the voltage regulator.