Multiconfigurable RF Codesigned GaAs MMIC Filter/Isolator/Switch (FIS)

K-band GaAs monolithic microwave integrated circuit (MMIC) multifunctional and multiconfigurable RF components that integrate the function of a quasi-elliptic bandpass filter (BPF), an isolator, and an RF switch filter/isolator/switch (FIS) with center frequency ( $f_{\text {cen}}$ ) and bandwidth (BW) tuning are reported. The proposed FISs are based on cascaded: 1) unilateral frequency-selective stages (UFSs) comprising a transistor-based path and multiresonant feedback, introducing one pole and two transmission zeros (TZs) and 2) reciprocal resonators that introduce one pole each. The UFS allows asynchronous TZ control, which can be exploited for BW tuning and intrinsic switching-off. $f_{\text {cen}}$ tuning is achieved by adjusting the poles of the UFSs and reciprocal resonators. A coupled-resonator-based synthesis methodology is introduced, extending conventional reciprocal filter synthesis to scalable UFS-based unilateral filters. For experimental validation, a two-stage FIS was manufactured using a 0.15- $\mu $ m GaAs process. The prototype demonstrates a quasi-elliptic response with $f_{\text {cen}}$ tuning between 17.3 and 19.5 GHz, 3-dB fractional BW tuning between 14.8% and 19.4%, gain of −3.9 to −1.9 dB, and directivity of 13–20 dB. In switching-off mode, it achieves >20-dB isolation over 17.7–19.7 GHz.