Patent ID: 7324787
Filing Date: 2008-01-29
Classification: H03G,H04L

Abstract:
1. A method of ramping up an output level of a power amplifier of a radio communication system having a transmission oscillator, a phase detection circuit for comparing a phase of a reference signal with a phase of a feedback signal to control the transmission oscillator in accordance with a detected phase difference, said power amplifier which amplifies an oscillation signal generated by the transmission oscillator, and an amplitude detection circuit for comparing an amplitude of a reference signal with an amplitude of a feedback signal to control the power amplifier in accordance with a detected amplitude difference, wherein the radio communication system transmits, by phase modulation, a transmission signal by using a phase control loop including the phase detection circuit, and transmits, by phase and amplitude modulation, a transmission signal by using the phase control loop and an amplitude control loop including the amplitude detection circuit, said method of ramping up an output level of a power amplifier comprising steps of: performing activation of the transmission oscillator, establishment of the phase control loop including the phase detection circuit, establishment of the amplitude control loop including the amplitude detection circuit, and ramp-up of the output level of the power amplifier, in this order recited, for activation of transmission related circuits; and lowering the output level of the power amplifier to a predetermined level higher than a level when the transmission related circuits are activated, while the transmission oscillator is maintained to operate, and thereafter ramping again the output level of the power amplifier without activation of the transmission oscillator, establishment of the phase control loop and establishment of the amplitude control loop, when transmission by phase modulation is switched to transmission by phase and amplitude modulation or when transmission by phase and amplitude modulation is switched to transmission by phase modulation, wherein after establishment of the phase control loop and before establishment of the amplitude control loop including the amplitude detection circuit, by using precharging means provided on a forward path in the amplitude control loop from the amplitude detection circuit to the power amplifier, the forward path is precharged up to a predetermined level faster than when an output of the amplitude detection circuit is used.