| 摘要 |
A method and an arrangement for correcting nonlinearity of an I/Q modulator in a linearization circuit of an amplifier of a transmitter, which circuit comprises an I/Q modulator (7) for I/Q-modulating a signal to be transmitted, a predistorter (3) for linearizing the amplifier (8), and a feedback arrangement (9, 12, 13, 14, 15 and 17) for determining parameters of the predistorter (3) of the amplifier (8), the arrangement comprising means (9) for sampling the I/Q-modulated measuring signal to be transmitted, 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 to be transmitted, 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 on the basis of the measuring signal fed into the I- and Q-branches of the transmitter and the I- and Q-feedback signals caused by the measuring signals, 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 of the I- and Q-branches of the I/Q modulator in order to compensate for the nonlinearity of the I/Q modulator.
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