Analysis and Design of a GaAs Monolithic Tunable Polyphase Filter in S/C Bands

AbstractThis paper proposes a new topology of a 2-Stages Active Polyphase Filter (APPF) in MMIC GaAs technology. This new topology, named “radial”, allows a greater balancing of output signals phases and amplitudes, over the actual APPF’s at the state of the art. In this paper an ex-novo study is shown and synthesis formulas for the APPF are provided. The MMIC simulations in 1-5GHz bandwidth show a tunable Image Rejection Ratio (IRR) greater than 40dB, a worst case input/output matching of 7.8dB and a maximum insertion loss of 10.8dB. By comparison with the tandem topology, as will be shown in the following, the radial one allows a significant improvement in the electrical performances