Collecting and amplifying circuit for floating weak currents

Abstract

The invention provides a collecting and amplifying circuit for floating weak currents. The circuit comprises a first operational amplifier, a second operational amplifier, a third operational amplifier, a fourth operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a ninth resistor and a variable resistor. The first operational amplifier, the second operational amplifier, the first resistor, the second resistor, the third resistor and the fourth resistor form a collecting circuit for collecting the floating weak currents and converting the currents into voltage signals, and the third operational amplifier, the fourth operational amplifier, the fifth resistor, the sixth resistor, the seventh resistor, the ninth resistor and the variable resistor form an amplifying circuit which is used for amplifying the converted voltage signals in a linear mode. The collecting and amplifying circuit for the floating weak currents can accurately collect the signals of the floating weak currents to be measured, convert the currents into the voltage signals, and amplify the signals in the linear mode, and the sequent signals processing is facilitated.

Description

technical field [0001] The invention relates to the field of electricity, and more specifically, to an acquisition and amplification circuit for floating weak current. Background technique [0002] Floating current is generally generated inside the sensor, instrument output, etc. Usually, these floating currents are relatively weak in magnitude, so they are called floating weak currents. The circuit model for this current can be represented as a current source. In order to reflect the characteristics of the actual current signal in the model, the model of the current source is limited as follows: the value is small and variable. The current signal must be generated in a closed loop, and if its magnitude is to be measured, the current must be closed into the measurement circuit. This will cause a problem: the measurement circuit usually has a certain input impedance, and this impedance is introduced into the loop of the circuit signal under test, which will weaken the curr...

AI Technical Summary

Problems solved by technology

This creates a problem: the measurement circuit usually has a certain input impedance, and this impedance is introduced into the loop of the signal of the circuit under test, which will weaken the current signal to be measured

If the input impedance of the measurement circuit is affected by the change of the current signal, the measured value will not only have a certain error, but also show nonlinear characteristics.

If it is amplified again, it will cause very serious distortion

[0003] At present, there are many schemes for collecting and amplifying floating weak current signals, but these schemes mainly have the following disadvantages: 1. The collection process affects the size of the current signal to be measured; 2. The amplification process affects the linearity of the measured value

The above two shortcomings lead to some distortion in the measurement results.

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