The present invention provides a high frequency power amplifier circuit
capable of obtaining sufficient detection output even in a range where a
request output power level is low and performing a desired output power
control by a control loop with the detection output in a radio
communication system which detects output power and performs feedback
control. An output power detection circuit which detects the level of
output power on the basis of an AC signal supplied from a final
amplification stage of a high frequency power amplification circuit via a
capacitive element has a circuit configuration such that in a state where
the output power control voltage is lower than a certain level, current
(Isu) according to the output power control voltage is generated and
supplied to the output power detection circuit, and detection sensitivity
of the output power detection circuit improves according to the current.