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一、概述 场效应晶体管的出现,为设计高输入阻抗半导体电路创造了有利条件。但在直流放大器中,零点漂移问题仍然是一个必须解决,而又不易解决好的问题。本放大器是为把小尺寸的压电陶瓷换能器用来测量缓慢变化的压力讯号而设计的一种高阻抗低功耗直流放大器。小尺寸的压电陶瓷换能器,在用来测量极低频讯号时,其内阻很大,因而要求放大器的输入阻抗特别高,在这样的条件下,换能器本身的热释电效应会产生非常严重的温度漂移。再加上场效应管和晶体管本身温度性能的不稳定性,就使得一般的直流放大器在此种条件下根本不能使用。
First, an overview of the emergence of field-effect transistors for the design of high-input impedance semiconductor circuit has created favorable conditions. But in the DC amplifier, zero drift problem is still a problem that must be solved, but not easy to solve. This amplifier is a high-impedance, low-power DC amplifier designed to measure a slowly changing pressure signal using small-size piezoelectric ceramic transducers. Small size of the piezoelectric ceramic transducer, used to measure very low frequency signal, the internal resistance is large, thus requiring the amplifier input impedance is particularly high, under such conditions, the transducer itself pyroelectric effect Produce a very serious temperature drift. Coupled with the FET and the transistor itself, the instability of the temperature performance, making the general DC amplifier can not be used under such conditions.