Thermal management for flip-chip high power amplifiers utilizing carbon nanotube bumps

Carbon nanotubes (CNTs) have been successfully used as source bumps for flip-chip high power amplifiers (HPAs). We have fabricated fine pitch CNT bumps with metal coating, which have been connected to electrodes close to the active areas of AlGaN/GaN HEMTs. A flip-chip AlGaN/GaN HEMT HPA with a gate width of 28.8 mm utilizing CNT bumps and an operating voltage of 50 V exhibits an output power of 49.3 dBm at a frequency of 2.4 GHz.