Abstract: In a radio communication system having a phase control loop for phase modulation and an amplitude control loop for amplitude modulation and being capable of time divisional transmission and reception under a predetermined time management, when transmission in a first mode is switched to transmission in a second mode or when transmission in the second mode is switched to transmission in the first mode, the output level of the power amplifier is lowered once to a predetermined level higher than the level when transmission related circuits are activated, and thereafter the output level of the power amplifier is again ramped after the settings have been changed but without starting of a transmission oscillator, establishing of the phase control loop and the amplitude control loop.

Abstract: If a transmission oscillator is incorporated into a communication semiconductor integrated circuit, such as high a frequency IC, constituting a wireless communication system, a problem arises. The accuracy of control of the output power of a power amplifier is degraded. This degradation in accuracy is caused by coupling noise between the output pins of the transmission oscillator and an input pin for detection signals (feedback signals) associated with the output level of the power amplifier or crosstalk. To prevent this, a transmission oscillator of differential output configuration is incorporated into a high frequency IC and an impedance equivalent to the impedance connected with a regular output terminal or a dummy external terminal for outputting transmit signals in opposite phase is provided.

Abstract: When a transmitting oscillator is built in a communication semiconductor integrated circuit device like a high-frequency IC constituting a wireless communication system, the system prevents degradation of the accuracy of control on the output power of a power amplifier due to noise jumped from an output pin of the transmitting oscillator to an input pin for a detected signal (feedback signal) of an output level of the power amplifier. The transmitting oscillator is built in the high-frequency IC. The detected signal of the output level of the power amplifier, which is detected by a coupler, is attenuated to a level slightly higher than the level of noise jumped from the output pin of the transmitting oscillator to the input pin for a feedback signal of an amplitude control loop, which in turn is inputted to the feedback signal input pin of the high-frequency IC.

Abstract: A polar-loop wireless communication apparatus includes, on a forward path between an amplitude detector and a power amplifier which constitute an amplitude control loop, a variable gain amplifier and a switch to change characteristics of a loop filter to output a frequency bandwidth of the amplitude control loop to an order less than an order for normal operation. The system is operated with the characteristics set to the lower order to measure outputs from the power amplifier to calibrate the output power of the power transmitter, and the register is operated with the characteristics set to the higher order to measure the open loop gain of the amplitude control. According to results of the calculation, data to correct gain characteristics of the variable gain amplifier with respect to an output control signal is stored in a nonvolatile memory of a baseband circuit.

Abstract: 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.