Differential-to-Single-Ended Converter With Noise-Balancing Feedback
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Solution Overview
Problem
Conventional differential to single-ended converters face issues with common-mode feedback circuit noises and large voltage swings at operational amplifier input terminals, degrading output signal linearity.
Innovation Solution
A differential to single-ended converter design incorporating a feedback circuit with a feedback resistor and operational amplifier, where the feedback circuit generates first and second feedback signals to control voltage swings and balance noise, ensuring small voltage swings at operational amplifier terminals and reducing noise influence on output signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a differential operational amplifier is used to convert differential signals to single-ended output, then the conversion function is achieved, but common-mode feedback circuit noises are introduced
Solution Approach 1:
The patent extracts and removes the common-mode feedback circuit from the differential operational amplifier configuration. By using a single-ended operational amplifier instead, the common-mode feedback circuit is eliminated entirely, preventing the introduction of CMFB noises into the output signal while maintaining the differential-to-single-ended conversion function.
Solution Approach 2:
The patent introduces a common-mode voltage generation circuit as an intermediary component. This circuit generates a stable common-mode voltage that is applied to the input terminals of the single-ended operational amplifier, serving as a mediator to handle the common-mode signal processing without requiring a common-mode feedback circuit, thus avoiding noise introduction.
2Device complexity
If a single-ended operational amplifier is used for differential to single-ended conversion, then the circuit complexity is reduced, but large voltage swing at input terminal degrades linearity
Solution Approach 1:
The patent introduces a feedback mechanism where the output signal is fed back to the non-inverting input terminal of the single-ended operational amplifier through a resistor. This feedback action stabilizes the voltage swing at the input terminal by counteracting large signal variations, thereby maintaining small voltage swings and preserving output signal linearity while keeping the circuit relatively simple.
Solution Approach 2:
The patent applies equipotentiality by generating a stable common-mode voltage and applying it to the input terminals. This creates a stable reference potential that prevents large voltage swings at the input terminal, ensuring that the operational amplifier operates in its linear region and maintaining output signal linearity without requiring complex circuit structures.
Data Source
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AI summary
The present invention provides a differential to single-ended converter including a first input node, a second input node, an operational amplifier (110) and a feedback circuit (120). The operational amplifier has a first terminal and a second terminal, wherein the first terminal of the operational amplifier (110) receives a first signal from the first input terminal, and the second terminal of the operational amplifier (110) receives a second signal from the second input terminal. The feedback circuit (120) is configured to receive an output signal of the operational amplifier (110) and generate a first feedback signal to the first terminal of the operational amplifier (110) to reduce a swing of the first signal, and generate a second feedback signal to the second terminal of the operational amplifier (110) to balance noises induced by the feedback circuit (120) and inputted to the first terminal and the second terminal.