A high-frequency circuit device is provided that achieves cost reduction
and reduction in power consumption and does not require an additional
high-frequency amplifier even when a transmission frequency band is newly
added. The high-frequency circuit device has a configuration including a
transmission amplifier circuit for transmitting high-frequency power from
an antenna, which includes at least one high-frequency amplifier for a
wide frequency band that amplifies signals in a plurality of transmission
frequency bands differing by not less than 200 MHz from each other, a
duplexer that is provided for performing simultaneous
transmission/reception, upstream and downstream switch circuits in the
direction of transmission that are provided so as to sandwich the
duplexer between the high-frequency amplifier for a wide frequency band
and the antenna and are switched on when the simultaneous
transmission/reception is performed, and a power supply amplitude
modulator that supplies an amplitude modulation voltage to a power supply
terminal of the transmission amplifier circuit.