LDO Regulator Noise Reduction Filter Circuit
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Solution Overview
Problem
Low-dropout (LDO) regulators face challenges in noise reduction, particularly when used to power noise-sensitive analog circuits, as existing solutions require external components and can affect the regulator's load and line transient response.
Innovation Solution
A linear voltage regulator design incorporating a first noise reduction filter, an error amplifier circuit, and a pass device, which generates a control signal based on a filtered reference signal and output voltage, effectively reducing noise without external components by using a voltage-controlled current source, filter capacitor, and filter switch, and a chopper-type error amplifier with duplicated error amplifiers to modulate and suppress 1/f noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If external capacitors or resistors are used for noise reduction, then noise is reduced, but device complexity increases and transient response is affected
Solution Approach 1:
The patent merges the noise reduction function with the existing LDO regulator structure by integrating a noise reduction filter directly into the regulator circuit. This combines voltage regulation and noise reduction into a single device, eliminating the need for external noise reduction components while maintaining simple device complexity and preserving transient response characteristics.
Solution Approach 2:
The patent introduces an intermediary noise reduction filter circuit that processes the reference voltage signal before it reaches the error amplifier. This intermediary filter reduces noise from the reference voltage source without requiring external capacitors or resistors, thereby reducing noise while maintaining simple device complexity and avoiding degradation of transient response.
2Object-affected harmful factors
If external capacitors or resistors are used for noise reduction, then noise is reduced, but the LDO's load and line transient response is affected
Solution Approach 1:
The patent merges the noise reduction function with the existing LDO regulator structure by integrating a noise reduction filter directly into the regulator circuit. This combines voltage regulation and noise reduction into a single device, eliminating the need for external noise reduction components while maintaining simple device complexity and preserving transient response characteristics.
Solution Approach 2:
The patent introduces an intermediary noise reduction filter circuit that processes the reference voltage signal before it reaches the error amplifier. This intermediary filter reduces noise from the reference voltage source without requiring external capacitors or resistors, thereby reducing noise while maintaining simple device complexity and avoiding degradation of transient response.
3Object-affected harmful factors
If noise reduction circuits are added to the LDO regulator, then noise is reduced, but device complexity increases
Solution Approach 1:
The patent merges the noise reduction function with the existing LDO regulator structure by integrating a noise reduction filter directly into the regulator circuit. This combines voltage regulation and noise reduction into a single device, eliminating the need for external noise reduction components while maintaining simple device complexity and preserving transient response characteristics.
Solution Approach 2:
The patent introduces an intermediary noise reduction filter circuit that processes the reference voltage signal before it reaches the error amplifier. This intermediary filter reduces noise from the reference voltage source without requiring external capacitors or resistors, thereby reducing noise while maintaining simple device complexity and avoiding degradation of transient response.
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
The solution achieves substantial noise reduction across a wide frequency bandwidth without affecting the LDO's load and line transient response, eliminating the need for external capacitors or resistors and enhancing the accuracy of noise-sensitive circuits.
Implementation Method 1
The first noise reduction filter may be configured to generate the filtered reference signal based on a reference voltage of a reference voltage source by reducing noise originating from the reference voltage source
Implementation Method 2
filter capacitor
Implementation Method 3
The error amplifier circuit may be configured to generate a control signal for controlling the pass device based on a filtered reference signal and an output voltage
Implementation Method 4
The pass device may be coupled between an input terminal of the regulator and an output terminal of the regulator
Data Source
AI summary
Linear voltage regulators and a method for low-dropout LDO regulators are presented. Specifically, LDO regulators with circuits for noise reduction are discussed. A linear voltage regulator has a first noise reduction filter, an error amplifier circuit, and a pass device. The pass device may be coupled between an input and output terminal of the regulator. The error amplifier circuit generates a control signal for controlling the pass device based on a filtered reference signal and an output voltage at the output terminal of the regulator. The first noise reduction filter generates the filtered reference signal based on a reference voltage of a reference voltage source by reducing noise originating from the reference voltage source or noise generated by one or more passive components coupled between the reference voltage source and the first noise reduction filter.