Patent ID: 7548116

Claim:
A high-frequency circuit comprising: a first PIN diode disposed in a signal line to which a high-frequency signal is introduced, one end of the first PIN diode on the high-frequency signal input side being connected to ground via a resistor; an amplifying device, an input end of the amplifying device being connected to the other end of the first PIN diode for a direct current; a bias circuit connected to the input end of the amplifying device; and a variable bias circuit to which a control voltage is supplied from a control voltage supply line, the control voltage being applied to the control voltage supply line in accordance with the signal level of the input high-frequency signal, the variable bias circuit generating a variable bias voltage in accordance with the control voltage and applying the variable bias voltage to the one end of the first PIN diode so as to control attenuation of the first PIN diode and control an operating current of the amplifying device.