Precise constant flow source based on differential amplifier and feedback buffer

Abstract

The invention discloses a precise constant flow source based on a differential amplifier and a feedback buffer. The precise constant flow source comprises an amplifier, an input resistor-feedback resistor integrated differential amplifier, a feedback buffer, a triode T2, a resistor Rref and a resistor Rload, wherein a reference voltage output circuit is connected to a positive input end of the differential amplifier, a negative input end of the differential amplifier is connected to the ground, an output end of the differential amplifier is connected to a base electrode of a triode T2, an emitting electrode of the triode T2 is connected with a SENSE wiring end of the differential amplifier, is sequentially connected to the resistor Rref and the resistor Rload and is connected to the ground, an voltage feedback input end of the differential amplifier is connected with an output end and negative input end of the feedback buffer, and a node between the resistor Rref and the resistor Rloadis connected with a positive input end of the feedback buffer. According to the precise constant flow source, the coherence of peripheral resistances is improved by virtue of the differential amplifier, and a current output loop and a voltage feedback circuit are isolated by virtue of the feedback buffer, so that the input impedance relative to outside of the differential amplifier is increased,and the current of the constant flow source is more accurate.

Description

technical field [0001] The invention relates to the technical field of precision constant current sources, in particular to a precision constant current source based on a differential amplifier and a feedback buffer. Background technique [0002] Precision constant current sources are required in many applications, including industrial process control, instrumentation, medical equipment, and consumer electronics, to name a few. For example, process control systems use constant current sources to provide the excitation current required by resistance temperature detectors; digital multimeters use constant current sources to measure resistance, capacitance, and diodes; long-distance information transmission systems use constant current sources to drive communication current loops. The quality of the constant current source directly determines the overall performance of these systems. Traditional constant current sources are basically constructed with operational amplifiers, re...

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Problems solved by technology

[0003] The purpose of the present invention is to provide a precision constant current source based on a differential amplifier and a feedback buffer, which is used to solve the inaccuracy of the traditional voltage-controlled constant current source caused by the consistency of resistance and the high input impedance of the amplifier in the prior art. high problem

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