A monolithic channelized preselector for EW receiver applications

A switched preselector, consisting of monolithic bandpass filters, multithrow switches, and broadband amplifiers, has demonstrated excellent selectivity and low loss characteristics in considerably less volume than conventional microstrip designs. The switches use series and shunt FETs in single-pole four-throw (1P4T) and single-pole double-throw (1P2T) configurations, while the filters were designed using semi-lumped-element techniques. A preselector filter bank with postamplification was designed that consisted of four 5-pole Chebyshev bandpass topologies, with center frequencies of 1.5, 2.8, 4.9, and 9.2 GHz, respectively, and bandwidths slightly less than an octave. The LC filter realizations were designed using monolithic parallel plate (MIM) capacitors and high-impedance transmission lines for inductors. Realization of the inductor values was simplified by using tapped inductor techniques simulating an autotransformer, thus enabling the designer to select a variety of transforming ratios. Excellent channel-to-channel isolation, switching speed, and sensitivities, comparable to those of other much larger hybrid approaches, were obtained.<>