Patent ID: 8451942

Claim:
A wireless transmission apparatus using a Cartesian loop, comprising: adder units configured to generate synthesized I/Q signals by synthesizing input I/Q signals to be transmitted, and feedback I/Q signals; a quadrature modulator unit configured to generate a quadrature modulated signal; a power amplifier unit configured to amplify the quadrature modulated signal and output a transmission RF signal; a quadrature demodulator unit configured to generate the feedback I/Q signals by applying quadrature demodulation using a local signal to a feedback RF signal branched from the transmission RF signal; a switch unit configured to be used to set ON/OFF of an input of the feedback I/Q signals to the adder units; an amplitude difference detector unit configured to generate an amplitude difference detection signal by detecting an amplitude difference between the input I/Q signals and the feedback I/Q signals during an OFF period of the switch unit; a phase difference detector unit configured to generate a phase difference detection signal by detecting a phase difference between the input I/Q signals and the feedback I/Q signals during the OFF period of the switch unit; a normalizer unit configured to generate a normalized phase difference signal by normalizing the phase difference detection signal by a signal amplitude of one of the input I/Q signals and the feedback I/Q signals; a power setting unit configured to set a power of the transmission RF signal; a control signal generator unit configured to receive the amplitude difference detection signal and the normalized phase difference signal, and generate an amplitude control signal that minimizes the amplitude difference and a phase control signal that minimizes the phase difference in a state in which the power is set during the OFF period of the switch unit; a memory unit configured to store the amplitude control signal and the phase control signal; an amplitude adjuster unit configured to adjust an amplitude of the feedback RF signal according to the amplitude control signal stored in the memory unit during an ON period of the switch unit; a phase adjuster unit configured to adjust a phase of the local signal according to the phase control signal stored in the memory unit during the ON period of the switch unit; and a gain setting unit configured to set, for the Cartesian loop, a first loop gain when the switch unit is OFF, and a second loop gain higher than the first loop gain when the switch unit is turned from OFF to ON.