Digital calibration of RF transceivers for I-Q imbalances and nonlinearity

As radio frequency (RF) devices become more complex, the specifications become more stringent. In order to guarantee successful operation and compliance to certain specifications, digital correction techniques that compensate the device impairments are needed. In this paper, we present an analytical digital in-phase (I) and quadrature (Q) imbalance and non-linear compression correction methodology that improves the system bit error rate (BER). The gain and phase imbalances are corrected by using the gain and phase imbalance test data obtained during the product testing. The non-linear compression term is removed using Newton´s method. The proposed test methodology is applicable for both burst based systems and continuous systems. Simulation results indicate that the proposed method improves the BER even under harsh noise contamination. The computational overhead of the compensation technique is minimal.