Widely linear estimation technique based on circularity for I/Q imbalance compensation in low-IF receivers

Compared with super-heterodyne architecture, one of the advantages of the low-IF receiver is that the image rejection is realized by I/Q signal processing instead of a fixed analog filter, making it highly integration, flexibility and cost-efficient. However, unavoidable imbalances between the I-branch and Q-branch lead to insufficient image attenuation which must be enhanced by using additional analog or digital signal processing. This paper proposes and analyzes a blind I/Q imbalance compensation scheme based on widely linear estimation technique, utilizing a property of the ideal IF signal called circular. Theoretical analysis and simulation results show that it can efficiently compensate for I/Q imbalance.