T-shaped resistance network trans-impedance amplification circuit with automatic voltage compensation function

Abstract

The invention discloses a T-shaped resistance network trans-impedance amplification circuit with an automatic voltage compensation function. The amplification circuit comprises a trans-impedance inputcircuit, a voltage follower circuit, a voltage gain circuit and a compensation voltage regulation network circuit. Compared with the prior art, the amplification circuit has the advantages that the T-shaped resistor network is adopted to realize an ultra-large resistance feedback resistor in the trans-impedance amplifier, and a high-resistance resistor which is high in price, high in installationand maintenance cost and large in error is abandoned; the voltage automatic compensation circuit is adopted to overcome a large offset voltage error introduced by a T-shaped resistor network, and meanwhile, an error generated by bias current through a large feedback resistor is eliminated, so that two problems are solved by one network; the circuit is completely completed by hardware, compared with the mode of collecting output voltage and then adjusting offset voltage through software, the circuit is simpler in structure, faster in zero setting and smaller in error, and the accuracy of weakcurrent measurement is greatly improved.

Description

technical field [0001] The invention relates to the field of electronic technology for general weak signal measurement, in particular to a T-type resistance network transimpedance amplifier circuit with automatic voltage compensation. Background technique [0002] In the field of general weak signal measurement electronics technology, the current measurement of fA to pA level usually uses an inverting amplifier circuit to convert the current into a voltage. Since the current is very small, the feedback resistance needs to reach the level of T ohms. Such a large resistance mainly brings about two problems. On the one hand, the bias current of the operational amplifier forms a voltage drop on the feedback resistor, which brings deviation to the output voltage. On the other hand, many T-ohm resistors require vacuum tube packaging, which is expensive and has high requirements for use. T-type resistor networks use low-value resistors to achieve large feedback resistors, which ca...

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Problems solved by technology

On the one hand, the bias current of the operational amplifier forms a voltage drop on the feedback resistor, which brings deviation to the output voltage

On the other hand, many T-ohm resistors require vacuum tube packaging, which is expensive and has high requirements for use. T-type resistor networks use low-value resistors to achieve large feedback resistors, which can be used to replace single resistors, but Compared with a single large resistor, in the T-type resistor network structure, the offset voltage has a huge impact, which often makes the measurement circuit directly enter the saturation state, seriously affecting the accuracy of the measurement results

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