An effort reduced six-port direct conversion receiver and its calibration

Well-known receiver architectures, such as wideband-IF-receivers or zero-IF-receivers, usually require highly accurate component matching. For the realization of a software defined radio (SDR) device, the requirement of adjustability supervenes. Contemporarily, much effort is being made to develop tunable circuits and also to find new algorithms for digital elimination of analog signal distortions, etc. In order to reduce the effort for the analog receiver front-end and to bridge the gap between system architectures and circuit technologies, the alternative six-port receiver was investigated. Based on the six-port structure, we present a five-port receiver front-end architecture with signal path mismatch cancellation. To be able to regenerate the IQ-components, a calibration technique is presented based on the proposed architecture. Therefore, known algorithms can be utilized after the calibration. The main focus is the technical feasibility of the front-end in SDR mobile terminals.