Ultralow noise analogue amplifier for three-dimensional resistivity acquisition system

Abstract

The invention relates to an ultralow noise analogue amplifier for a three-dimensional resistivity acquisition system, which comprises two parts. The first part is a directly coupled voltage series negative feedback ultralow noise amplifier consisting of six transistors; the second part is a low noise amplifier consisting of three operational amplifiers; in the first part, an emitting electrode on the second stage provides bias currents for base electrodes on the first stage; when the bias currents are obtained, DC (Direct Current) negative feedback is introduced, so that a static working point of a circuit is more stable; a capacitor is added into a bias feedback circuit, so that an input impedance of an amplification circuit is greatly improved; the second part is formed by two in-phase input universal integrated operational amplifiers of which the performance parameters are highly consistent, adopts double-end signal input and single-end signal output, has a very high common mode rejection ratio and a very good effect on interference suppression on an electromagnetic field and can enable the measurement accuracy to reach below 0.1muV, so that weights of field transmitting equipment and receiving equipment can be greatly reduced and working efficiency of electrical prospecting is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of geophysical exploration, and relates to an ultra-low noise analog amplifier used in a three-dimensional resistivity data acquisition system in the technical field of resource and environmental exploration. Background technique [0002] The three-dimensional resistivity data acquisition system belongs to the direct current method exploration instrument. The development of direct current prospecting instrument technology is inseparable from the development of electric prospecting theory, electronic technology, signal processing technology and computer technology. Direct current prospecting instruments have gone through a development process similar to other instruments, from mechanical to electronic tube and transistor stage, to integrated circuit and microcomputer control stage. [0003] With the gradual development of mineral resource exploration to the deep, the required exploration depth is getting lar...

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Problems solved by technology

[0004] The working conditions of direct current prospecting instruments are in the field, especially for mineral resource exploration, which may be in areas with high mountains, dense forests, and criss-cross rivers, or desert areas with few people. The heavy transmitter equipment reduces work efficiency and even makes it impossible to carry out work.

In the direct current method prospecting instrument system, in order not to make the high-voltage, high-current transmitter power too large and make the equipment too heavy, it is necessary to improve the measurement sensitivity and measurement accuracy of the instrument receiver, and to improve the sensitivity and accuracy of the instrument receiver. Accuracy, the noise of the pre-amplifier in the instrument must be as low as possible, and the current domestic similar product instrument receiver measurement sensitivity and measurement accuracy are in the order of 0.1-0.9mV

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