Reference Voltage Circuit Third-Order Feedback Loop
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Solution Overview
Problem
High-precision integrated circuits, such as A/D converters, face challenges in maintaining reference voltage accuracy due to weak power supply rejection ratios, especially under large power supply voltage fluctuations.
Innovation Solution
A reference voltage circuit is designed with a third-order negative feedback loop comprising a reference core unit, a main amplification unit, and a feedforward amplification unit, enhancing the power supply rejection ratio through a high-gain feedback loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional reference voltage circuit is used, then the circuit structure is simple, but the power supply rejection ratio is weak and the reference voltage accuracy deteriorates under power supply fluctuations
Solution Approach 1:
The patent implements a third-order negative feedback loop by introducing a feedforward amplification unit with feedback connection to the reference core unit. This feedback mechanism continuously monitors and corrects reference voltage deviations caused by power supply fluctuations, significantly improving the power supply rejection ratio while maintaining circuit stability through the high-gain feedback path.
Solution Approach 2:
The patent transitions from a conventional second-order feedback structure to a third-order feedback structure by adding the feedforward amplification unit. This dimensional enhancement in the feedback loop order provides an additional control dimension, enabling the system to achieve superior power supply rejection performance without compromising stability.
2Measurement precision
If the feedback loop order is increased to third-order, then the power supply rejection ratio is improved, but the circuit complexity increases
Solution Approach 1:
The patent divides the amplification function into two separate units: a main amplification unit and a feedforward amplification unit. This segmentation allows each unit to be optimized for specific functions, with the feedforward unit handling the power supply rejection enhancement while the main unit maintains the core reference voltage generation, thereby managing complexity through functional decomposition.
Solution Approach 2:
The feedforward amplification unit serves multiple functions: it provides the third-order feedback path for improved power supply rejection, maintains the reference voltage accuracy, and works synergistically with the main amplification unit. This multi-functionality justifies the added complexity by delivering multiple performance benefits from a single structural addition.
Data Source
AI summary
Reference voltage circuits and methods for designing the same are provided. The reference voltage circuit includes: a reference core unit configured to output a reference voltage; a main amplification unit connected to the reference core unit and configured to form feedback to the reference core unit; and a feedforward amplification unit connected to the main amplification unit and configured to form feedforward to the main amplification unit. The reference core unit, the main amplification unit, and the feedforward amplification unit form a third-order negative feedback loop to improve a power supply rejection ratio of the reference voltage.