High-Power RF Pallet and Transistor Solutions for Radar and Avionic Systems from UHF to S-Band

Avionic systems (eg IFF and TACAN) typically require a few kW of output power under specific pulse conditions. With the advent of multi-kW GaN on SiC transistors designed for these systems the designer now has the option of either eliminating the need for a combiner, or else only needing a two-way compared with a four-way or higher combiner. This leads to smaller systems with higher efficiency. Also, RF amplifier pallets are an alternative way of realizing these systems whereby the equipment manufacturer out-sources the RF design, and these pallets may also incorporate digital control in which parameters such as output power level are monitored or controlled along with temperature, pulse conditions etc. On the other hand, radar systems are often phased arrays in which each element only needs to transmit an output power of a few hundred watts at most, but often at high duty cycle and long-pulse lengths. This imposes a thermal limit on the transistor, and the frequency of operation imposes a size constraint. Additionally, legacy UHF phased array radar utilizing LDMOS TX amplifiers can be replaced with higher voltage and higher efficiency GaN SiC amplifier pallets. The efficiency gains are such that the system can transmit greater that 3dB more RF power with the similar power consumption over LDMOS. This presentation will review the state-of-the-art in transistors and pallet amplifiers for these various systems.