Mirrored Current Feedback Interface Circuit for Low Input Impedance
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Solution Overview
Problem
Existing interface circuits in switch mode power converters face challenges in reducing input impedance, which limits circuit performance due to resistance that cannot be reduced by conventional methods without violating system specifications.
Innovation Solution
Implementing a mirrored current feedback mechanism using a current mirror and shunt feedback to reduce input impedance without altering the original components of the input circuit path, effectively decreasing impedance through a closed-loop system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If shunt feedback with mirrored current is applied, then input impedance is reduced, but device complexity increases due to additional current mirror circuitry
Solution Approach 1:
The patent applies shunt feedback by mirroring the input current through a current mirror circuit and feeding it back to the inverting input terminal. This feedback mechanism reduces the input impedance of the operational amplifier by creating a virtual ground effect, where the feedback current cancels the input current, effectively lowering the impedance seen at the input terminal without requiring physical changes to the input circuit path.
2Difficulty of detecting and measuring
If input impedance is reduced by changing input circuit path impedance, then input impedance decreases, but the impedance of the input circuit path is altered which may affect other circuit parameters
Solution Approach 1:
The feedback mechanism allows input impedance reduction while keeping the input circuit path impedance unchanged. The current mirror circuit creates a feedback current that is proportional to the input current, and this feedback current is subtracted from the input current at the inverting terminal, effectively reducing the input impedance without modifying the physical characteristics of the input circuit path.
Solution Approach 2:
The current mirror circuit acts as an intermediary between the input signal and the feedback path. It copies the input current and delivers it to the feedback network, enabling impedance transformation without directly modifying the input circuit path. This intermediary mechanism preserves the original input circuit path impedance while achieving the desired input impedance reduction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The mirrored current feedback approach enhances switching performance and increases system bandwidth by reducing input impedance, thereby improving circuit efficiency and functionality.
Implementation Method 1
Shunt feedback via a return circuit path provides a mirrored current to an interface input thereby reducing an input impedance of the interface circuit
Data Source
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AI summary
An interface circuit using mirrored current feedback to reduce input impedance is disclosed herein. According to the teachings herein, the interface circuit includes a current mirror and an input circuit path. Shunt feedback via a return circuit path provides a mirrored current to an interface input thereby reducing an input impedance of the interface circuit. By virtue of shunt feedback, the input impedance of the interface circuit is reduced relative to the impedance of the input circuit path. In this manner, input impedance of the interface circuit may be reduced without changing the impedance of the input circuit path.