Direct Chip Mounting GaAs Power Module using an AIN Substrate

A new power amplifier module (PAM) in which GaAs power MESFETs are mounted directly on an aluminum nitride (AIN) substrate has been developed for analog cellular phones. This module occupies a volume of 0.2cc, only 1/4 as large as that of conventional one, and can deliver an output power (Pout) of 31dBm with a power-added efficiency (PAE) of 58% at a low operating voltage of 3.5V around 900MHz band. Furthermore, a new microwave probe card has been introduced into on-wafer RF power measurement of the FETs in order to improve the yield of the PAMs. Using this probe card, the maximum output power of 30.9dBm has been obtained, and gain deviation between on-wafer and packaged FETs is only 1.4dB. This new concept PAM and the developed on-wafer measurement technique must promise advanced high-performance PAM.