Gain/phase imbalance compensation for multi-band quadrature receivers

This paper presents a compensation technique for the gain/phase imbalance of quadrature demodulators for direct conversion receivers. The power measurements for the imbalance estimation can be done in less than ten symbol periods of the test signals. This means that the compensation method does not need many iterative cycles using the least mean square method or discrete Fourier transform that previous methods need. Experimental results show that the differences between the estimated and actual values are small: the gain imbalance was 0.3 dB, and the phase imbalance was 1.1°.