GaN based RF Modules - Demands Needs for Packaging

摘要

GaN/SiC based powerbars and MMICs are the youngest semiconductor devices which have arrived inthe field of Radio Frequency modules and applications, e.g. radar, communication links and highpower transmitters and amplifiers. Nearly 5 years ago, the first GaN devices were used in the fields oftelecommunication equipment, mainly in base-station amplifiers and today GaN devices are more andmore part of modern radar applications, like T/R (Transmit/Receive) modules in AESA (ActiveElectronically Scanned Array) antennas.The main advantages of GaN/SiC semiconductor devices in comparison to GaAs-devices are thehigher bandwidth, higher robustness level and the higher operation voltage. Another big issue of GaNis the higher power density, with in minimum 4 times higher values compared to GaAs. Therefore theassembly of GaN MMICs and powerbars on heatsinks and module-baseplates is a big challenge forsoldering technology. An absolute minimum of voids between backside of the GaN/SiC devices andthe heatsink is necessary to guarantee an optimised heat transfer during operation.Different package materials and technologies are on the market and big international packagesuppliers deal with new material combinations, like sandwich structures of Cu and Mo. Materials likeAl-diamond are used for heatsink materials and with special tests and measurements the results ofheat 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.