30 Watt surface-mount power amplifiers for PCS and UMTS applications

Small surface-mount power amplifiers have been developed that produce 30 Watts of peak power in the PCS and UNITS frequency bands. These two-stage amplifiers exhibit typical gain of 28 dB with good linearity and efficiency under CDMA signal protocols (typically -49 dBc ACPR and 20% efficiency at 5W average IS95A CDMA output). The designs involve a combination of chip-and-wire plus SMT lumped and distributed matching elements on a thick-film substrate. The thermal design includes two levels of heat spreading through metal base elements before the PCB attachment interface. FET maximum channel temperatures for PCB mounted devices are typically 121 degreesC for 5W average CDMA output with a +85 degreesC base temperature. The 30W peak power is believed to be the highest reported for a commercial surface-mount amplifier operating in a microwave band.