LDO Regulator Feedback Circuit for Wide-Band PSRR Improvement
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Solution Overview
Problem
Conventional low dropout (LDO) regulators in integrated circuits face challenges in maintaining stable voltage and suppressing wide-band noise and ripple signals, particularly in systems-on-chip (SOC) applications, leading to poor performance and high frequency bandwidth issues.
Innovation Solution
The proposed solution involves an LDO regulator configuration that includes an operational amplifier, an output circuit, a feedback circuit, and compensation circuit, along with divided resistors, which provides feedback paths to cancel ripple signals and improve power supply rejection ratio (PSRR) by coupling feedback signals back to the operational amplifier, thereby reducing the impact of ripple signals on the output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LDO regulator configuration is used, then device complexity is reduced, but power supply rejection ratio and ripple suppression performance deteriorate
Solution Approach 1:
The patent introduces a feedback path that couples the output node back to the inverting input terminal of the operational amplifier. This feedback mechanism allows the regulator to detect and correct ripple signals and noise at the output, thereby improving power supply rejection ratio and voltage stability without requiring complete redesign of the regulator architecture.
Solution Approach 2:
The patent introduces a compensation capacitor as an intermediary element connected between the inverting input terminal and the output node. This capacitor acts as a mediator that filters high-frequency noise and ripple signals, enabling improved PSRR performance while maintaining the basic LDO regulator structure.
2Object-affected harmful factors
If simple LDO regulator structure is used, then manufacturing is easier, but wide-band noise and ripple suppression capability deteriorates
Solution Approach 1:
The feedback path directly couples output ripple signals back to the operational amplifier's inverting input, where they are subtracted from the reference voltage signal. This active feedback mechanism effectively reduces the impact of ripple signals on the output without requiring complex passive filtering components.
Solution Approach 2:
The patent modifies the electrical parameters of the regulator by adding the feedback path and compensation capacitor, which changes the frequency response and impedance characteristics of the circuit. This allows the regulator to maintain low output impedance across a wide frequency range, improving ripple suppression capability.
Data Source
AI summary
A device is disclosed. The device includes an operational amplifier, an output circuit and a first feedback circuit. The operational amplifier includes an input terminal that is configured to receive a feedback signal. The output circuit is coupled to an output terminal of the operational amplifier and is configured to generate an output signal in response to an output of the operational amplifier. The first feedback circuit is coupled to the output circuit and is configured to couple at least one first ripple signal in the output signal to the input terminal of the operational amplifier that is configured to receive the feedback signal, for adjusting the output signal. A method also is disclosed herein.