A fully integrated triple-band CMOS power amplifier for WCDMA mobile handsets

The recent rapid spread of smart-phone use has resulted in a strong demand for a multi-band RF part with reduced size and power consumption. In the creation of an ideal RF system-on-a-chip, the biggest challenge is to realize a fully integrated PA in CMOS. In conventional PAs in compound semiconductor technologies, face-up wire-bond assembly with off-chip matching components is typically used, but flip-chip packaging is more suitable for slim mobile phones in which low-profile components are desired as well as for future integration with an RF transceiver in which the same packaging scheme is widely used. The PA for GSM [1] was insufficient for our target, so we needed to greatly improve the linearity in order to comply with the W-CDMA standard, which has better frequency-usage efficiency. Conventional CMOS PAs only support a single band [2,3] or are for WLAN [4] where the output power level is low (typically about 20dBm). In this paper, we present a fully-integrated triple-band linear CMOS PA for W-CDMA. Its flip-chip package is just 3.5×4×0.7mm³, and the average current consumption is less than 20mA.