Low Noise Current Buffer Circuit with Feedback Capacitor
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Solution Overview
Problem
Conventional current voltage converters, such as bandgap reference circuits, are susceptible to noise interference from system voltage, causing output voltages to be unstable and deviate from a stable range.
Innovation Solution
A low noise current buffer circuit incorporating a first and second current mirror and a feedback capacitor forms a negative feedback loop to mitigate the impact of system voltage noise on output voltage, ensuring stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional current source is used to output current to generate output voltage, then the circuit structure is simple, but the output voltage is affected by noise of system voltage and cannot stay within a stable range
Solution Approach 1:
The patent introduces a feedback capacitor connected between the drain of the fourth transistor and the gate of the first transistor, forming a negative feedback loop. This feedback mechanism detects output voltage variations caused by noise and adjusts the current output accordingly, stabilizing the output voltage and resolving the contradiction between reliability and complexity.
Solution Approach 2:
The patent employs current mirrors as intermediary components between the current source and the output resistor. The current mirrors act as mediators that isolate the output from direct noise coupling while maintaining current transfer, thereby improving output voltage stability without significantly increasing overall circuit complexity.
2Reliability
If the system voltage rises rapidly due to noise, then the transistors output greater input currents, but the output voltages exceed the stable range
Solution Approach 1:
The feedback capacitor creates a negative feedback loop that detects when output voltage exceeds the stable range due to noise-induced current increases. The feedback signal adjusts the transistor gate voltages to reduce the current output, counteracting the noise effect and maintaining output voltage within the stable range.
Solution Approach 2:
The feedback mechanism anticipates and counteracts noise effects before they significantly destabilize the output. By continuously monitoring and adjusting the current output in response to voltage variations, the system preemptively corrects deviations caused by system voltage noise.
Data Source
AI summary
A low noise current buffer circuit includes a first transistor, for receiving an input current, a second transistor, for draining a first current from a drain of the second transistor according to the input current received by the first transistor, a third transistor, for outputting first current, a fourth transistor, for outputting a second current to an output resistor, to generate an output voltage, and a feedback capacitor, for eliminating impacts of noise of a system voltage on the output voltage.