| 摘要 |
PURPOSE:To perform automatic precise electric power control by setting the reference voltage from a reference voltage generating circuit stepwise automatically at a high speed with a reference voltage indication signal. CONSTITUTION:An input signal from an input terminal 6 is passed through a variable attenuator 7 and amplified at a part 8, whose output appears at a terminal 10 through a directional coupler 9. The coupler 9 extracts part of the output electric power of the amplifier 8, and a DC voltage is detected by a detector 11. This DC voltage and the output voltage of a referece voltage generating circuit 13 are compared mutually in an operational amplifier 12, whose output difference controls the extent of attenuation of the attenuator 7. A variable resistor 17 is connected between the power input terminal 15 and reference voltage output terminal 16 of the circuit 13, switching resistances 19-21 are connected in parallel to the resistor 17, and a fixed resistance 18 is further connected between the connection point and ground point. Consequently, the reference voltage is set by four stages automatically at a high speed by an indication signal from an external terminal. |
