A Self-Calibration Method of I/Q Mismatch in Direct-Conversion Transceiver

Gain imbalance and phase skew between I/Q signals in direct-conversion transceiver is the one of key issue in communication field. These impairments introduce an unwanted in-band image component interference and degrade the performance of communication system. This paper proposes a method to realize estimating and compensating I/Q mismatch in transceiver. This method can distinguish different signals by generating different local frequencies between transmitter and receiver, which are phase locked to the same reference clock. Thus, the parameters of gain imbalance and phase skew can be estimated by using training sequence via a closed loop channel in transceiver. Meanwhile, the path transmission characteristic interference of the closed loop channel from the output of modulator in transmitter to the front end of demodulator in receiver can be eliminated. Finally, the frequency-dependent of the transmitter’s I/Q mismatch can be estimated by using the algorithm described in this paper. The results of simulations show that gain imbalance and phase skew in transmitter can be determined directly, and present the effectiveness of the method.