Patent attributes
The present invention provides a power amplifier that includes the following: an RF operation transistor 3 having a base to which an RF signals is inputted, an emitter connected to the ground, and a collector connected to a power supply and a terminal for outputting an RF signal; a current reference transistor 12 having a collector connected to a reference current source 11, an emitter connected to the ground, and a base connected to the base of the RF operation transistor, an operational amplifier 22 formed of CMOS having one input connected to the collector of the current reference transistor and the other input connected to the base of the RF operation transistor; and a voltage-to-current conversion transistor 22 for converting the output of the operational amplifier 22 into a current to be supplied to the base of the RF operation transistor. The power amplifier has low power consumption and an efficient use of chip area, and a current variation due to the relative variation in hFE can be prevented, so as to be driven with a low power supply voltage.
