| 摘要 |
PURPOSE:To stabilize operation by providing plural differential amplifier circuits for detection which input an emitter voltage and a reference voltage and a phase adding circuit which sums up respective differential output components of those differential amplifier circuits for detection. CONSTITUTION:If a signal supplied to an input terminal 1 exceeds a specific level. an impulsive voltage is developed at the common emitter of the 3rd differ ential amplifier circuit 13 for detection and applied to the base of a transistor (TR) Q13a, so that collector currents which contain AC components with the different polarities flow through TRs Q13a and Q13b. Then, the collector currents are I0/2+i and I0/2-i, where I0 is the value of a current supplied from the common emitter of the circuit 13 and (i) is the AC component of the collector currents. Therefore, only an AC component 2i appears at an output terminal 2 and is smoothed by a capacitor C1 to obtain a level detection output. Thus,the differential outputs are obtained at the respective collectors of the 3rd-the 1st amplifier circuits for detection in order as the input signal rises in level, and the sum of them is outputted 2.
|
