Abstract: A varactor comprising two Schottky diodes, each diode comprising a substrate and a plurality of layers formed on the substrate including at least one GaN layer and at least one semi-insulating material layer formed of a material with an energy gap greater than 3.5 and free carrier mobility less than 300 cm2/V-s; the Schottky diodes having cathodes adapted to be connected to an AC voltage input and being configured so that as the AC voltage applied to the cathodes increases the capacitance decreases nonlinearly, the nonlinear transition from high capacitance to low capacitance being adjustable by utilizing the intrinsic carrier concentration of the semi-insulating layer to obtain an optimal nonlinear transition for the predetermined AC voltage applied to the cathodes. A method of making a varactor comprising computer modeling to produce capacitance-voltage curves, modifying at least one semi-insulating region, and modeling power input/output efficiency for a predetermined input signal.

Abstract: A varactor comprising two Schottky diodes, each diode comprising a substrate and a plurality of layers formed on the substrate including at least one GaN layer and at least one semi-insulating material layer formed of a material with an energy gap greater than 3.5 and free carrier mobility less than 300 cm2/V-s; the Schottky diodes having cathodes adapted to be connected to an AC voltage input and being configured so that as the AC voltage applied to the cathodes increases the capacitance decreases nonlinearly, the nonlinear transition from high capacitance to low capacitance being adjustable by utilizing the intrinsic carrier concentration of the semi-insulating layer to obtain an optimal nonlinear transition for the predetermined AC voltage applied to the cathodes. A method of making a varactor comprising computer modeling to produce capacitance-voltage curves, modifying at least one semi-insulating region, and modeling power input/output efficiency for a predetermined input signal.

Abstract: A preferred method of optimizing a Ga-nitride device material structure for a frequency multiplication device comprises: determining the amplitude and frequency of the input signal being multiplied in frequency; providing a Ga-nitride region on a substrate; determining the Al percentage composition and impurity doping in an AlGaN region positioned on the Ga-nitride region based upon the power level and waveform of the input signal and the desired frequency range in order to optimize power input/output efficiency; and selecting an orientation of N-face polar GaN or Ga-face polar GaN material relative to the AlGaN/GaN interface so as to orient the face of the GaN so as to optimize charge at the AlGaN/GaN interface. A preferred embodiment comprises an anti-serial Schottky varactor comprising: two Schottky diodes in anti-serial connection; each comprising at least one GaN layer designed based upon doping and thickness to improve the conversion efficiency.

Abstract: A waveguide-to-microstrip transition package (30) for processing electromagnetic wave signals includes a waveguide (32) for directing the signals to the input of the waveguide (32). A substrate (34) overlaps the input of the waveguide (32) to form a hermetic seal. A metallized probe (36) conducts the signals to a microstrip line (40) and is patterned upon the substrate (34). The transition (30) also includes an iris (48) formed from a metallized pattern on the opposite side of the substrate (34) from the probe (36). The special design of the probe (36), the structure of the iris (48) and the wave guide cavity (46) above the probe (36) allow impedance matching and efficient signal transfer from waveguide (32) to microstrip line (40) or from microstrip line (40) to waveguide (32).