Abstract:
Design of electronically tunable filters at UHF band is presented. Design techniques for two different filter topologies namely combline and interdigital are studied and compared. In the design of tunable Filters, the goal is to achieve good tuning range with compact size, minimum achievable insertion loss (I.L) and suppression of harmonics.
In this thesis design and analysis of 3rd order tunable bandpass filter is implemented using interdigital and combline filter topologies. Design of Interdigital and combline tunable bandpass filter is performed using K & Q method implemented in method of moments based EM analysis (Momentum) in ADS. Both the designs are analyzed for filter parameters like compact size, I.L, rejection and harmonics. Interdigital filter achieved low I.L and moderate tuning range whereas combline filter has wide tuning range and moderate I.L.
In case of combline filter, tuning is achieved from 288 MHz (I.L ~3.48dB) to 460 MHz (I.L ~1.29dB) and in case of interdigital filter, tuning is achieved from 383 MHz (I.L ~3.22 dB) to 545 MHz (I.L ~1.55dB) with voltage levels from 1 Volt to 10 Volts and 1 Volt step of each.
