High frequency amplification circuit and mobile communication terminal using the same

摘要

A gain control circuit 12 comprises an FET 41 operating as a variable resistor. A gate terminal of the FET 41 is supplied with a control voltage VC applied to a gain control terminal 23 . A source terminal and a drain terminal of the FET 41 are supplied with a reference voltage Vref 1 obtained by a reference voltage circuit 13 . The reference voltage Vref 1 is controlled so as to compensate for a variation in the threshold voltage of the FET 41 . The resistance value of the FET 41 is changed in accordance with the control voltage VC, and thus the gain of the high frequency amplification circuit 10 is also continuously changed.