GaN based RF Modules - Demands & Needs for Packaging

GaN/SiC based powerbars and MMICs are the youngest semiconductor devices which have arrived in the field of Radio Frequency modules and applications, e.g. radar, communication links and high power transmitters and amplifiers. Nearly 5 years ago, the first GaN devices were used in the fields of telecommunication equipment, mainly in base-station amplifiers and today GaN devices are more and more part of modern radar applications, like T/R (Transmit/Receive) modules in AESA (Active Electronically Scanned Array) antennas. The main advantages of GaN/SiC semiconductor devices in comparison to GaAs-devices are the higher bandwidth, higher robustness level and the higher operation voltage. Another big issue of GaN is the higher power density, with in minimum 4 times higher values compared to GaAs. Therefore the assembly of GaN MMICs and powerbars on heatsinks and module-baseplates is a big challenge for soldering technology. An absolute minimum of voids between backside of the GaN/SiC devices and the heatsink is necessary to guarantee an optimised heat transfer during operation. Different package materials and technologies are on the market and big international package suppliers deal with new material combinations, like sandwich structures of Cu and Mo. Materials like Al-diamond are used for heatsink materials and with special tests and measurements the results of heat transfer studies will be shown. In this paper examples of power amplifiers, operating in the frequency range of 2–6 GHz and 6–18GHz, and a typical X-Band Frontend will be shown and the RF results will be discussed.