Tunable Active Microwave Bandpass Filters Using Three-Terminal MESFET Varactors.

摘要

Two types of tunable active bandpass filter working at X-band are presented. Both circuits employ the concept of three-terminal MESFET varactor. The first circuit uses two MESFETs of which one is used to generate a negative resistance and the other is used to generate a variable reactance. The second circuit uses only one MESFET which has both functions of those two MESFETs in the first circuit. The achievement of using one MESFET to replace two MESFETs with different functions provides a significant advantage. It reduces the number of solid-state elements needed in the active circuits and thus simplifies the fabrication of the circuits.