| 摘要 |
PURPOSE:To attain stable characteristic of an amplifier circuit by proving an operational amplifier and a constant voltage diode to a bias circuit of a high frequency transitor (TR) so as to stabilize the high frequency characteristic of the TR against the fluctuation in power supply voltage. CONSTITUTION:The bias circuit for the high frequency TR is provided with a TR3 of common emitter and a collector of the TR3 is connected to a power supply DC via a resistor R9. Further, a non-inverting input of the operational amplifier IC2 is connected to a collector of the TR3 and an output terminal of the amplifier IC2 is connected to the base of the TR3. Further, the power supply DC is connected to an inverting input of the amplifier IC2 via a Zener diode X1. Then, the diode X1 is grounded via a resistor R8. Thus, the high frequency characteristic of the TR3 is made stable against the voltage fluctuation in the power supply DC thereby stabilizing the characteristic of the amplifier circuit. |
