A Compact Bandpass Filter Manifold with Ultrawide Frequency and Bandwidth Tuning

Abstract

This paper reports a comprehensive design methodology and a compact multilayer integration concept for a fully-reconfigurable bandpass filtering (BPF) manifold with simultaneous ultrawide center frequency and bandwidth (BW) tuning. The manifold is based on two RF-switched tune-all BPFs whose transfer function is shaped by three-poles and two transmission zeros (TZs) (i.e., three-pole/two-TZs). Tunability can be achieved by solely reconfiguring the resonant frequency of its constituent resonators (i.e., tuning-coupling less approach). A multi-layer PCB-based vertical integration scheme is proposed for size miniaturization leading to 43% smaller area than a conventional single layer implementation approach. For practical validation purposes, a BPF manifold was designed, built and measured. It exhibited ultrawide continuous center frequency tuning between 1.8 and 3.85 GHz (2.2:1) and continuous BW tuning between 2.5-3:1 (e.g 132-410 MHz at 2 GHz). For all of the aforementioned tuning states, the minimum passband insertion loss (IL) was measured between 2-9 dB and its IIP3 between 12.3-30 dBm.