Direct Baseband I-Q Regeneration Method for Five-Port Receivers Improving DC-offset and Second-Order Intermodulation Distortion Rejection

Abstract : Six/Five-port architecture has advantages compared to conventional receiver architectures, especially for high frequencies and high data rate applications. However, it requires two/one additional baseband outputs and a calibration process to recover the original signal. While this problem is resolved in conventional six-port configurations, a solution is needed for five-port architectures. We propose an I/Q regeneration method based on the use of a simple analog circuit, eliminating one baseband output. The structure of this circuit derives from a mathematical formulation, which is presented in this paper. The validity of the method has been experimentally proved in a five-port receiver prototype. In addition, its capacity to reduce the DC-offset and second-order intermodulation distortion (IMD2) has been demonstrated.