A polar loop based radio telecommunication apparatus which has a phase control loop for controlling the phase of a carrier outputted from an oscillator for transmitter, and an amplitude control loop for controlling the amplitude of a transmission output signal outputted from a power amplifier circuit, wherein precharge means is provided on a forward path from a current source, through the power amplifier circuit, to a detection circuit, forming the amplitude control loop, for rapidly increasing a control voltage for the power amplifier circuit to a power threshold upon starting transmission.