Compensation of component mismatch in RF receivers using digital techniques

The quadrature IF receiver topology is utilized in direct conversion and low-IF receivers. In theory the quadrature IF topology eliminates the need for the image filters required by the heterodyne topology. In practice mismatch in analog components between the I and Q signal paths allows leakage of image energy into the desired signals band. This leakage limits the performance of the quadrature IF receiver. This paper utilizes a two-input two-output LTI equivalent model of the mismatched receiver. Based on the equivalent model an architecture to suppress the image leakage caused by the analog mismatch in the I and Q signal paths is proposed. The model-based image suppression is validated through simulation and shown to provide good performance.