Microwave frequency agile active filters for MIC and MMIC

Abstract

Microwave-frequency agile active resonators which, in a planar structure, can be realized using microwave integrated circuit (MIC) or monolithic MIC (MMIC) technologies are presented. Consisting of modified hairpin resonator feedback by an amplifier and a phase shifter, these resonators offer extremely-low-loss and high-Q-value resonators. The use of varactors permits a tuning of the resonant frequency as well as the bandwidth. Using such resonator, a bandstop filter with a rejection of 45 dB and a lossless bandpass filter with a return loss of 35 dB have been obtained at 3.1 GHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>