Wireless communication apparatus having a phase control loop shared by first and second modulation modes and an amplitude control loop
View Patent ↗A transmitter adopting a polar loop system including a phase control loop for controlling the phase of a carrier signal outputted from a transmitting oscillator and an amplitude control loop for controlling the amplitude of a transmitting output signal outputted from a power amplification circuit, and designed to be capable of performing transmission using a GMSK modulation mode and transmission using an 8-PSK modulation mode. In the transmitter, the phase control loop is shared as a phase control loop for use in the GMSK modulation mode and a phase control loop for use in the 8-PSK modulation mode. A component similar to any one of components constituting a loop filter is provided in parallel therewith so that the component can be connected or disconnected in accordance with the modulation mode, for example, by use of a switching element.
1. A wireless communication apparatus comprising:
a base band circuit for generating I and Q signals in accordance with transmitting data;
a transmitting oscillator for generating a carrier signal;
a power amplifier for amplifying the carrier signal outputted from the transmitting oscillator;
a power detector for detecting a power level of a transmitting output signal from the power amplifier; and
a semiconductor integrated circuit for modulation including an orthogonal modulator for modulating the I and Q signals onto the carrier signal so as to form an oscillating signal of a predetermined frequency, a phase control loop which has a phase detector and controls a phase of the carrier signal, and an amplitude control loop which has an amplitude detector and controls an amplitude of the transmitting output signal,
wherein the phase control loop includes a feedback path for supplying a signal in accordance with an output of the power detector,
wherein the amplitude control loop includes the feedback path for supplying a signal in accordance with an output of the power detector, and
wherein the wireless communication apparatus has a first modulation mode and a second modulation mode, and wherein the phase control loop is shared by the first modulation mode and the second modulation mode.
2. The wireless communication apparatus according to claim 1 ,
wherein the first modulation mode is a phase modulation mode using the phase control loop, and
wherein the second modulation mode is a phase and amplitude modulation mode using both of the phase control loop and the amplitude control loop.
3. The wireless communication apparatus according to claim 1 , wherein the phase detector further includes a digital phase detection circuit.
4. The wireless communication apparatus according to claim 1 , wherein the amplitude control loop further includes:
a first variable gain amplifier provided on the feedback path between the power detector and the amplitude detector and for amplifying the signal; and
a second variable gain amplifier provided on a forward path between a second loop filter and the power amplifier;
wherein a gain of said first variable amplifier is set in accordance with an output control voltage in the second modulation mode while a gain of the second variable gain amplifier is controlled inversely to that of said first variable gain amplifier.