X-Band MMIC-Based Tunable Quasi-Absorptive Bandstop Filter

Abstract

This letter reports on the design and experimental testing of a new class of tunable monolithic microwave integrated circuit (MMIC)-based quasi-absorptive bandstop filters (ABSFs). An asynchronous tuning method is used to improve the design robustness and obtain an ultrahigh stopband attenuation over a wide tuning range. RF tuning is facilitated by GaAs pHEMT varactors. The proposed filter configuration exhibits the following unique features: 1) ultrahigh stopband rejection (>70 dB) despite using low quality factor lumped element (LE) resonators; 2) miniaturized footprint enabled by the GaAs MMIC process and the use of LE-based impedance inverter elements; and 3) frequency agility. An X-band filter prototype was manufactured using a commercially available GaAs process. It exhibits a high isolation notch whose center frequency can be tuned between 8.7 and 10.5 GHz while having >40-dB attenuation and a maximum attenuation of 73.6 dB.

Capacitive Tuning of High Selective T-Shaped Band-Stop Filter: Theory and Experiment

“…Integrating graphene oxide with T-shaped TL BSF results in switching between two frequencies, corresponding to the high and low states of the graphene oxide memristor [9]. Monolithic microwave integrated circuit (MMIC)-based quasi-absorptive bandstop filters (ABSFs) provide high rejection tunable BSF with low tuning range [10], but the structures are complex. However, for frequency tuning, a varactor is common [2], [10]-…”

“…Monolithic microwave integrated circuit (MMIC)-based quasi-absorptive bandstop filters (ABSFs) provide high rejection tunable BSF with low tuning range [10], but the structures are complex. However, for frequency tuning, a varactor is common [2], [10]-…”

Resonator-Loaded Waveguide Notch Filters with Broad Tuning Range and Additive-Manufacturing-Based Operating Frequency Adjustment Procedure

“…Electrical, magnetic, and mechanical tuning methods have been employed in the literature to create tunable planar and 3D filters [5]. The majority of research efforts have been focused on planar tunable notch filters based on substrate-integrated waveguides (SIW), coplanar waveguides (CPW), and cavity resonators [6][7][8][9][10][11].…”

“…In [8], a notch filter that can be tuned from 3 GHz to 3.6 GHz using an evanescent mode cavity was designed; this represents a tuning range of about 18 percent. With the use of GaAs pseudomorphic high-electron-mobility-transistor (pHEMT) varactors, a novel category of tunable monolithic microwave integrated circuit (MMIC)-based quasi-absorptive notch filters was constructed in [9]. It has a strong isolation notch with a center frequency that is adjustable from 8.7 GHz to 10.5 GHz.…”