Electret microphone current test circuit and test method thereof

Abstract

The invention discloses an electret microphone current test circuit, including a direct current power supply, a digital potentiometer, a first analog switch, a calibration resistor, an electret microphone, a signal conditioning part, a second analog switch, a digital full-amplitude modulation part and a high-performance alternating current coupling data acquisition card. The direct current power supply, the digital potentiometer, the analog switches, the calibration resistor and the electret microphone form a loop, the signal conditioning part consists of a first operational amplifier, a second operational amplifier and a third operational amplifier, the first operational amplifier and the second operational amplifier are connected with the digital full-amplitude modulation part through the second analog switch, and the digital full-amplitude modulation part and the third operational amplifier are connected with the high-performance alternating current coupling data acquisition card. The invention also proposes a test method of the electret microphone current test circuit, and through calculation of an actual Res value of a line and calculation of a microphone current, solves the problem existing in a present electret microphone current test method that a test result is inaccurate.

Description

【Technical field】 [0001] The invention relates to the technical field of microphone current testing, in particular to an electret microphone current testing circuit and a testing method thereof. 【Background technique】 [0002] The electret microphone is a capacitive acoustic-electric transducer, which consists of two parts: acoustic-electric conversion and impedance conversion. The acoustic-electric conversion part is a capacitor formed by an electret material film and a metal plate, and they are separated by a thin insulating ring. The key component is the electret material film, which adopts a pre-polarization method to Charge is permanently stored in the electret material. When sound waves act on the electret film, the capacitance changes. Since the capacitance between the electret film and the metal plate is small, generally only on the order of tens of picofarads, its low-frequency output impedance can reach several Ten megaohms or even hundreds of megaohms. However,...

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Problems solved by technology

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art. For the data acquisition card system for collecting AC signals, a kind of electret microphone current test circuit and its test method are provided, which aims to solve the traditional electret in the prior art. There is a technical problem of inaccurate test results in the test method of bulk microphone current

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