| 摘要 |
PURPOSE:To improve the frequency characteristic by making the gain variable by controlling a current flowing to a load resistance of an emitter ground amplifier circuit, and also supplying a current which is short in a collector of the emitter ground amplifier circuit through a diode of a compensating means from a reference voltage. CONSTITUTION:A fundamental emitter ground amplifier circuit is formed by a transistor (TR) 23, a resistance 21 and a resistance 24. When a control voltage VCONT impressed to a base of a TR 20 is varied, a current I flowing to the resistance 21 is varied. When this DC current I is varied, the gain of the emitter ground amplifier circuit is varied. Also, a diode 25 is a circuit for replenishing a collector current of the TR 23, which becomes short by a control, and a current is replenished to the collector of the TR 23 through the diode 25 from a voltage VREF. In this way, an AGC circuit having a good frequency characteristic without using a PIN diode can be formed. |
