Fully Differential Amplifier Feedback Circuit for Stable Gain Ratio
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Solution Overview
Problem
Conventional fully differential amplifiers have limited bandwidth and are sensitive to transconductance variations, which affect gain ratio and amplifying performance, especially in transistor-based designs where large resistances are needed to minimize transconductance influence, leading to reduced output current and performance.
Innovation Solution
A transistor-based fully differential amplifier with a variable gain function is designed, incorporating a feedback circuit module with NMOS transistors and electrical current sources to increase equivalent transconductance and reduce the impact of semiconductor component drifting on gain ratio, allowing for higher amplification ratios and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large resistance R21 is used to minimize transconductance influence on gain ratio, then gain ratio stability is improved, but output current decreases and amplifying performance is limited
Solution Approach 1:
The patent changes the parameter of resistance value by using different resistance ratios (R21/R22 = 2, 4, 8, 16, 32, 64) to study the influence on gain ratio stability and output current, allowing optimization between these two conflicting parameters
Solution Approach 2:
The patent applies partial action by using moderate resistance ratios (starting from K=2) rather than excessively large ratios, achieving sufficient gain ratio stability while maintaining adequate output current for amplifying performance
2Reliability
If transconductance Gm is not significantly increased, then resistor resistance R21 must be increased to minimize transconductance influence, but this limits amplifying performance
Solution Approach 1:
The patent systematically varies the resistance ratio parameter K to find the optimal balance point where gain ratio stability is achieved without excessively compromising amplifying performance
Data Source
AI summary
A differential amplifier is provided in the present invention. The differential amplifier includes an amplifying module having a resistive ratio, receiving an input voltage, and amplifying the input voltage as an output voltage in accordance with the resistive ratio; and a feedback module coupled with the amplifying module and generating a feedback signal in accordance with the input voltage and the output voltage for regulating the output voltage.