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.

Abstract: A method and arrangement for correcting a phase error in a linearization loop of a power amplifier, the loop comprising an I/Q modulator (10), one or more delay-causing power amplifiers (13) to be linearized, an I/Q demodulator (11) for generating I and Q feedback signals from the output signals of the amplifier (13), difference means (20, 21) of the I and Q branches for generating I and Q difference signals from the I and Q feedback signals and the I and Q input signals, the I/Q modulator and the I/Q demodulator receiving an oscillator frequency from the same local oscillator (14), and a phase shifter (17), the method comprising determination of a phase error resulting from the delay produced in the linearization loop, which determination comprises feeding excitation signals to the I and Q inputs (I IN, Q_IN) of the linearization loop, measuring the signals resulting from the excitation signals and calculating a phase error by means of the measured signals and excitation signals, and correcting the phase err

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.