DESIGN AND DEVELOPMENT OF ACTIVE COMBLINE FILTER

Abstract

This dissertation reports the design and development of an active combline filter for frequency range of operation 0.7 GHz - 1.9 GHz. Tuning was achieved by introducing varactor diode (SMV 1234-011 LF) and the losses due to the microstrip resonator and varactor are compensated by generating negative resistance with the help of pHEMT ATF-34143 transistor. Another active combline filter for frequency range of operation 1.5 GHz - 2 GHz is designed and the tuning was achieved by introducing varactor diode(SMV1232-011LF) ) and the losses due to the microstrip resonator and varactor are compensated by generating negative resistance with the help of HJ-FET NE3509M04 transistor. Commercially available simulation tool Agilent ADS Momentum(2.5D) and EMDS(3D) were used in the modeling of this novel device.