On‐chip GaAs‐based dual‐band bandpass filters/isolators (DBPFIs)

Abstract

AbstractMMIC co‐designed RF components exhibiting the collocated RF signal processing actions of a dual‐band bandpass filter and an RF isolator (DBPFI) are presented. They are based on in‐parallel cascaded bandpass filters/isolators that operate at two different frequencies and two multi‐resonant cells that are added in the RF input and RF output to increase the selectivity and the out‐of‐band isolation of the DBPFI through six added transmission zeros. For proof‐of‐concept demonstration purposes, a DBPFI prototype was designed and manufactured using a commercially available GaAs MMIC process. It exhibited the following RF‐measured characteristics: center frequencies: 8.14 GHz and 10.8 GHz, 3‐dB fractional bandwidth (FBW): 11.1% and 16.4%, |S21|: −3.7 dB and −8.8 dB, isolation >36.6 dB and 16.5 dB, IP1dB: 11.8 dBm and 12.8 dBm, IIP3: 18.2 dBm and 16.5 dBm, and OIP3: 14.2 dBm and 6.7 dBm, respectively, at the lower and the upper band.