| 摘要 |
PURPOSE:To increase the dynamic range of the circuit and to stabilize the frequency characteristics, by using a saturable impedance between the collector and the emitter of two pairs of transistors as a variable impedance circuit. CONSTITUTION:The current value of a constant current source 15 is changed, the impedance between the collector and the emitter of transistors (TR)13, 14 is changed and the gain is controlled by changing the current shunting ratio between a signal current is and the input signal current to a differential amplifying circuit. The impedance circuits 16, 17 reduce the variance of the maximum gain due to the variance of the current amplification factor of the TRs 13, 14 of differential amplifier stage at the maximum gain. |
