Effects of hardware imperfection on six-port direct digital receivers calibrated with three and four signal standards

Online calibration is essential for the proper operation of six-port digital receivers in communication systems, as such calibration cancels out receiver ageing and manufacturing defects. Simple calibration methods, using only three or four signal standards (SS), were reported in a previous paper, where these methods were assessed using an ADS software simulation for an ideal six-port circuit. A unified and general theory is presented for examining the effects of hardware imperfection on the performance of a six-port receiver (SPR) calibrated using these simplified techniques. This can be used to establish permissible hardware tolerances for proper operation of SPRs in different digital modulations.