Abstract: A method and an arrangement for determining correction parameters used for correcting DC-offset of an I/Q modulator in a transmitter comprising an I/Q modulator and a corrector for correcting the DC-offset caused by the I/Q modulator are presented. The method comprises sampling the I/Q-modulated test signals, which are formed from I/Q-plane test vectors, A/D-converting the signal samples taken from the test signals, I/Q-demodulating the signal samples digitally into I- and Q-feedback signals, determining the DC-offset caused by the I/Q modulator on the basis of the test vectors and the feedback vectors caused by the test vectors and formed from the I- and Q-feedback signals, and determining the correction parameters of DC-offset on the basis of the determined DC-offset.

Abstract: A method and an arrangement for determining correction parameters used for correcting phase and amplitude imbalance of an I/Q modulator in a transmitter comprising an I/Q modulator (7) and a corrector (4) for correcting the phase and amplitude imbalance caused by the I/Q modulator, the arrangement comprising means (9) for sampling the I/Q-modulated test signal to be transmitted, means (14) for A/D-converting the signal samples taken from the test signal, means (15) for I/Q-demodulating the signal samples digitally into I- and Q-feedback signals, means (17) for determining the phase and amplitude imbalance caused by the I/Q modulator on the basis of the I- and Q-feedback signals, and means (17) for determining the correction parameters of phase and amplitude on the basis of the determined phase and amplitude imbalance.

Abstract: A method and an arrangement for correcting nonlinearity of an I/Q modulator in a linearization circuit of an amplifier (8) of a transmitter, which circuit comprises an I/Q modulator (7), a predistorter (3), and a feedback arrangement (9, 12, 13, 14, 15 and 17), the arrangement comprising means (9) for sampling the I/Q-modulated measuring signal, which is formed from the measuring signals fed into the I- and Q-branches of the transmitter, means (14) for A/D-converting the signal samples taken from the signal, means (15) for I/Q-demodulating the signal samples digitally into I- and Q-feedback signals, means (17) for determining the nonlinearities of the I- and Q-branches of the I/Q modulator, and means (4A, 4B, 16A and 16B) for predistorting the I- and Q-signals supplied to the I/Q modulator (7) separately by means of the determined nonlinearities.