PURPOSE: To attain stably a broad band, by providing an impedance adjusting circuit utilizing a differentiating resistor of a diode so as to adjust externally the peaking characteristics or the tuning characteristics.
CONSTITUTION: A series feedback amplifying circuit having an input terminal 2 and an output terminal 4 is formed with an input transistor 6, a load resistor 7 and a series feedback resistor 8. Further, the impedance adjusting circuit 41 comprising a diode 22, a capacitor 9, and a constant current source 17 is connected between a high potential power supply terminal 1 and a low power supply terminal 2. The impedance of the adjusting circuit 41 is changed by a signal at a terminal 23. Since the gain of this amplifying circuit is expressed approximately with equation, the peaking characteristics are made variable by the signal at the terminal 23.
ISHIHARA NOBORU
OBARA MAMORU
| JPS539235U | 1978-01-26 |