A Low Loss and Area Efficient RC Passive Poly Phase Filter for Monolithic GHz Vector-Sum Circuits

In this brief, type-II RC poly phase filters (PPFs) are investigated as the I/Q network of a vector-sum phase shifter. In a system analysis, it has been shown that it is possible to improve the phase shifter performance by simultaneously accepting some gain error and decreasing phase error. Moreover, the degree of freedom resulting from the non-zero gain error allows to reduce the loss of poly-phase circuits. Accordingly, a new structure of PPF has been proposed to improve the multi-stage PPF circuits for use in the vector-sum phase shifter, which reduced the loss and area without significantly changing the phase shift performance. Finally, a two-stage PPF has been designed that has a 30% smaller area than the conventional type-II PPF, while the loss has decreased more than 0.6 dB.