A type of lumped-element-based analog filters based on transversal circuit networks

Abstract

A novel technique to design lumped-element-based analog filters is presented. It exploits the application of signalinterference principles to a class of transversal filtering section made up of two in-parallel discrete-element transmission lines. This circuit network, through destructive and constructive signalenergy interactions, enables high-selectivity filtering actions to be generated. Moreover, this can be done in the same circuit topology independently of the type of transfer function to be synthesized. Design equations and guidelines for this lumped-element analog filter approach are given. Besides, for experimental validation, simulation results of two synthesis examples consisting of a lowpass and a bandpass filter implemented at the layout level are shown.

Hybrid surface‐acoustic‐wave/microstrip signal‐interference bandpass filters

“…losses associated to real discrete components at microwave frequencies, so that bandwidths as narrow as those attainable through the engineered SAW/microstrip BPFs become practically unrealisable with the approaches of [19,20]. Furthermore, as it will be experimentally demonstrated, more-abrupt cut-off slopes can be attained with the current mixed-technology signal-interference BPFs when compared with those in [19,20] by partially transferring the ultra-sharp-rejection capabilities of the embedded SAW device to the overall transfer function.…”

“…It should be further noticed that other recently proposed signalinterference BPFs, such as the ones in [19,20] in which the entire transmission-line pathsconventional type in [19] and left-handed type in [20] implemented in multi-layer liquid-crystal-polymer technologyare replaced by their lumped-element equivalents, are also unsuitable for very-narrow-band applications. This is due to the IET Microwaves, Antennas & Propagation…”