| 摘要 |
PURPOSE:To prevent reduction in output dynamic range and to eliminate distortion and deterioration by compensating a bias current decrement of a differential amplifier transistor (TR) by means of a bypass TR so as to make a collector DC operating point constant. CONSTITUTION:A DC level from a detector 6 is inputted to TRs 7, 8 constituting a comparator and an inverting collector output of the TR8 is inputted to a TR4 and a diode 5 of a constant current circuit of differential amplifier's TRs1, 2 via a diode 11 and a TR12. on the other hand, a non-inverting collector output of a TR7 is inputted to constant current circuit diode 15 of bypass TR pairs 17, 18 and a TR16 via a diode 13 and a TR14. Thus, the current of the same value as the bias current reduction due to the AGC so as to eliminate deterioration of distortion due to dynamic range reduction. |
