A UHF Weak Signal Combined Amplifying Circuit

Abstract

The invention belongs to the field of on-line monitoring of electrical equipment ultrahigh frequency local discharging, and particularly relates to a novel ultrahigh frequency weak signal combined amplification circuit.The circuit comprises a signal end, a noise end, a differential noise-reducing pre-amplification circuit, a signal amplification circuit, a first biasing circuit, a second biasing circuit and an output end, the high-symmetry differential amplification circuit is adopted for the differential noise-reducing pre-amplification circuit to perform differential noise-reducing processing and signal amplifying on an input signal and a noise signal, and the noise end is placed at the position away from monitoring equipment, so that background noise is filtered away to the maximum; two-stage amplification design is adopted for the signal amplification circuit, the signal amplification factor of the first stage is 102-104, and the signal amplification factor of the second stage is 103-106; a filtering device is arranged in the circuit, so that a needed signal is amplified, and meanwhile the noise signal is reduced to the maximum; the measurement precision of the weak signal can reach the level of microamp and even reach the level of nanoampere.

Description

technical field [0001] The invention belongs to the field of on-line monitoring of ultra-high frequency partial discharge of electric equipment, and in particular relates to an ultra-high frequency weak signal combination amplifier circuit. Background technique [0002] At present, the major power companies in my country are changing the maintenance mode of power equipment from regular maintenance to condition maintenance. Timely and accurate grasp of the operation status of power equipment is the primary task of online monitoring of equipment. Through on-line partial discharge detection of equipment, the insulation status of power equipment can be quickly and timely grasped, and the blindness of equipment maintenance tests can be reduced. The monitoring frequency band of the UHF detection method is generally 300MHz~3GHz, and the background noise of the power equipment use site and the corona discharge frequency band in the air are all below 300MHz, which can effectively avo...

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Problems solved by technology

[0003] The main problem faced by the UHF weak signal amplifying circuit in the prior art in the measurement of weak signals is that the measurement accuracy is not enough. It is relatively high accuracy to be able to measure mA-level current or other physical quantities of the same magnitude, and it is resistant to Weak interference ability and low reliability

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