An MMSE based calibration of LINC transmitter

This paper proposes a new correction technique for the LInear amplification with Nonlinear Components (LINC) transmitters. The technique, which is based on the minimum mean squared error (MMSE) criterion, estimates the gain and phase imbalance between the two amplifier branches. With information on the estimation, the imbalance is compensated by controlling the amplitude and phase of the input signal that is fed into one of the two amplifiers. Computer simulations with the QPSK modulation demonstrate that this method can calibrate the balance and sufficiently suppress the out-of-band distortion spectra.