To suppress the increase of current consumption and the problem of heat generation accompanying voltage drop in the case of using the high frequency IC of a low power supply rated voltage.

Transistors 101, 102 and 103 operated by a first power supply rated voltage of 15 V are cascade connected over plural stages from an input stage and the high frequency IC 104 operated by a second power supply rated voltage of 5 V lower than the first power supply rated voltage is connected to the final stage. A constant voltage circuit 105 for supplying the second power supply rated voltage to the high frequency IC 104 is provided and the respective emitter output of the plural transistors 101-103 are connected in common to the input of the constant voltage circuit 105.