Patent ID: 8514914

Claim:
An IQ imbalance correction method, which is executed in a wireless communication device comprising a quadrature modulator and a quadrature demodulator in an analog circuit area, comprising: transmitting a plurality of pairs of radio frequency, RF training signals in separate transmissions by pairing RF training signals symmetric with respect to a center frequency on a frequency axis; controlling a reception local frequency of the quadrature demodulator in the analog circuit area to change to a frequency that is used to receive in the quadrature demodulator in the analog circuit area, via an internal path, each of the plurality of pairs of RF training signals transmitted in the separate transmissions, and to convert each of the plurality of pairs of RF training signals into intermediate frequency, IF training signals; performing analog/digital conversion on the IF training signals by an analog/digital converter and then performing quadrature demodulation on the IF training signals, which have been analog/digital converted, in a quadrature demodulator in a digital circuit area to generate baseband, BB training signals; calculating transmission correction coefficients for correcting IQ imbalance of a transmitter, which includes the quadrature modulator, based on signals obtained from demodulating the BB training signals using a demodulator in the digital circuit area; correcting the IQ imbalance of the transmitter using a transmission correction coefficient, which added the calculated transmission correction coefficients together, for an entire frequency range; transmitting the plurality of pairs of RF training signals at once for correcting IQ imbalance of a receiver, which includes the quadrature demodulator in the analog circuit area, after correcting the IQ imbalance of the transmitter; controlling the reception local frequency to change to the same frequency as a transmission local frequency, and demodulating the plurality of pairs of RF training signals that have been transmitted at once into BB training signals by direct quadrature demodulation in the quadrature demodulator in the analog circuit area; calculating reception correction coefficients for correcting the IQ imbalance of the receiver based on signals obtained from analog/digital conversion of the BB training signals performed using analog/digital converters and subsequent demodulation of the analog/digital converted BB training signals using the demodulator in the digital circuit area; and correcting the IQ imbalance of the receiver using the reception correction coefficients.