Semiconductor integrated circuit for communication, radio-communication apparatus, and transmission starting method
View Patent ↗In a polar loop based radio-communications apparatus having a phase control loop for controlling the phase of a carrier outputted from an oscillator for transmission, and an amplitude control loop for controlling the amplitude of a transmission output signal outputted from a power amplification circuit, the phase control loop is first started while maintaining the amplitude control loop in an off state at the outset of transmission, and the amplitude control loop is started after stabilizing the phase control loop.
1. A radio communication apparatus comprising:
a base band circuit which generates first signals to be transmitted;
a high frequency integrated circuit which modulates the first signals;
a power amplifier which amplifies a transmission signal; and
a coupler which detects an output power of the power amplifier,
wherein the high frequency integrated circuit includes:
a modulator which performs phase modulation and amplitude modulation to the first signals;
a phase detector which detects a phase component of an output of the modulator;
an amplitude detector which detects an amplitude component of the output of the modulator;
a feedback path which supplies a second signal corresponding to the output power of the power amplifier from the coupler to the amplitude detector;
a forward path which supplies an output of the amplitude detector to the power amplifier;
a variable gain amplifier which generates a control voltage for amplitude control based on the output of the amplitude detector to the power amplifier;
a loop filter which is arranged between the amplitude detector and the variable gain amplifier and which sets a frequency bandwidth of an amplitude control loop, the amplitude control loop including the feedback path and the forward path; and
a sequencer which generates control signals sequentially and supplying the control signals to associated circuits for operating the circuits in a predetermined order based on a command supplied from the base band circuit.
2. A radio communication apparatus according to claim 1 , wherein
the sequencer supplies the control signals to start a phase control loop while maintaining the amplitude control loop in an off state upon starting transmission, and to start the amplitude control loop after the phase control loop is stabilized.
3. A radio communication apparatus according to claim 1 , further comprising:
an oscillator which is arranged between the high frequency integrated circuit and the power amplifier and which oscillates in accordance with an output of the a phase detector and outputs the transmission signal.
4. A radio communication apparatus according to claim 1 , wherein
the high frequency integrated circuit is formed on a single semiconductor chip.