Linear Regulator With Dual Feedback Paths For Noise Rejection
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Solution Overview
Problem
Signal processing systems, such as audio processing systems, are adversely affected by noise from power supplies, particularly due to frequency components that coincide with the systems' operation, leading to performance degradation.
Innovation Solution
A voltage regulation system with a high power supply rejection response over a wide frequency range is implemented, utilizing a linear regulator architecture that includes an error amplifier, a voltage-controlled current source, and a compensation capacitor to provide a regulated voltage and decouple noise from sensitive circuitry, maintaining stability and phase margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional linear regulator is used, then the circuit is simple, but the power supply rejection is poor at high frequencies leading to noise coupling into sensitive circuitry
Solution Approach 1:
The feedback network is segmented into multiple paths: a first feedback path with a capacitor providing high-frequency noise rejection, and a second feedback path with a voltage-controlled current source providing additional rejection mechanisms. This segmentation allows each path to target specific frequency ranges, improving overall power supply rejection without requiring complete redesign of the regulator.
Solution Approach 2:
A compensation capacitor is introduced as an intermediary element in the feedback network. This capacitor acts as a mediator that filters high-frequency noise from the feedback signal, preventing it from reaching the error amplifier and being amplified. The intermediary capacitor effectively blocks harmful high-frequency components while allowing legitimate feedback signals to pass through.
2Object-affected harmful factors
If feedback networks are added to improve power supply rejection, then noise coupling is reduced, but the phase margin and stability may deteriorate
Solution Approach 1:
The invention changes the electrical parameters of the feedback network by introducing specific capacitive elements and voltage-controlled current sources with carefully selected characteristics. These parameter changes create frequency-dependent feedback that attenuates voltage ripple at noise frequencies while maintaining adequate phase margin at frequencies critical for stability. The parameter optimization ensures both noise rejection and stability coexist.
3Object-affected harmful factors
If multiple feedback paths are implemented, then power supply rejection over wide frequency range is improved, but the device complexity increases
Solution Approach 1:
The feedback network is designed with multi-functional elements that serve multiple purposes simultaneously. The compensation capacitor provides both high-frequency noise filtering and phase compensation. The voltage-controlled current source contributes to both power supply rejection and loop stability. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in overall device complexity while achieving broad frequency-range power supply rejection.
Data Source
AI summary
A voltage regulation system includes an error amplifier configured to generate an error amplifier output based on a reference voltage, input voltage, first feedback voltage, and second feedback voltage. The feedback voltages are based on a first output voltage at the system's output node. The system further includes a capacitor configured to provide the first feedback voltage to the error amplifier. The system further includes a voltage-controlled current source configured to generate a current based on the first output voltage. The second feedback voltage is based on the current. The system further includes a transistor configured to provide a second output voltage at the output node based on the error amplifier output. The transistor is connected to the output node and the capacitor. Such a voltage regulation system may allow a high power supply rejection response over a wide range of frequencies and loads while maintaining stability and phase margin.