The signal reception circuit and the optical impulse reception circuit null which uses this

摘要

PURPOSE:To prevent malfunction by using an automatic threshold control circuit so as to apply peak-hold to a signal voltage superimposing a minute voltage to a divided input signal voltage using the peak hold value as a threshold voltage and comparing the threshold voltage with an input signal voltage at a voltage comparator, thereby eliminating the influence of noise or the like. CONSTITUTION:A voltage resulting from superimposing a minute voltage onto a divided input signal voltage at an automatic threshold level control circuit A is fed to a peak-hold circuit 14, in which the voltage is subjected to peak hold and a threshold voltage is obtained. Thus, when the fluctuation of the input signal voltage is generated, the threshold voltage is controlled so as to be a divided voltage compared at a voltage comparator 3 in response to a level change when the level fluctuation of the input signal voltage takes place, the production of pulse width distortion resulting from level fluctuation of the input signal voltage is prevented and a threshold voltage in response to a very small voltage is generated even at non-signal through the superimposition of the minute voltage. Thus, the influence due to noise or the like is eliminated to prevent malfunction.