Ion implanted SiC static induction transistor with 107 W output power and 59% power added efficiency under CW operation at 750 MHz

There are many commercial applications which require high RF CW power in the kilowatt to megawatt range. To date, these high RF power requirements can only be accomplished by incorporating traveling wave tubes (TWT) or inductive output tubes (IOT). However, recent advances in the output power capability of SiC power devices for radar systems now suggest that high power SiC static induction transistors (SIT) can be used to develop a 10 kW solid state RF power amplifier. From analysis of existing high power RF amplifiers, development of a transistor cell that can produce 10 W CW output power would provide the necessary building block for assembly of a 10 kW power amplifier. As a first step in this development, existing ion implanted SiC SIT device cells fabricated at Northrop Grumman were packaged and tested for CW operation at 750 MHz. Identical transistor die from a single wafer of ion implanted SIT devices were selected, each having a layout of 10 device cells per die, with each cell having a gate periphery equal to 1.30 cm, and an active area of 2.92 × 10^-4 cm². To minimize heating under CW operation, only 10 cells were bonded into a transistor package. This was accomplished by attaching only 2 die to a package, and wire bonding every other cell in each die. In this manner, only 5 cells from each die were connected together, and the remaining 5 cells were not used, thus allowing for improved heat spreading.