Electronically adjustable bandpass filter

[摘要] ENGLISH ABSTRACT: This thesis presents the study, analysis and design of electronically tunable filters, that can be tuned over a widefrequency range (20-500MHz), for use in a direct sampling receiver. The final design does not have to be asingle filter, but may be comprised of a filter bank which enables switching between the filters. The band ofinterest is too low to use normal transmission lines and lumped elements have to be used. Different topologiesthat can implement Coupled Resonator filters with lumped elements are investigated. Devices that can be usedfor tuning are also investigated and varactor diodes are found to be the most suitable tuning devices currentlyavailable. Two filters, one at the high-end and one at the low-end of the band, were designed and built, bothusing varactor diodes. These filters perform well in terms of tuning range, but achieving low losses with currenttechnologies in this band remains difficult.

[发布机构] Stellenbosch University