A Fully Integrated 2 $,\times,$ 2 Power Amplifier for Dual Band MIMO 802.11n WLAN Application Using SiGe HBT Technology

A fully monolithic 2 times 2(2 times 5 GHz-band, 2 times 2.4 GHz-band) power amplifier (PA) implemented in a 0.18 mum Silicon Germanium (SiGe) HBT process has been developed for a dual band MIMO 802.11n WLAN system. In order to achieve the required performance for the 5 GHz band while maintaining a high level of integration, different approaches have been investigated. A special Through-Wafer-Via (TWV) process on Si wafer was developed and utilized for this 2 times 2 PA. From fabricated 2 times 2 chip measurement results, both 5 GHz-band and 2.4 GHz-band PAs show above 17 dBm linear power output for -28 dB EVM and more than 18 dBm with >14% efficiency for 5 GHz-band and 19% efficiency for 2.4 GHz-band at -25 dB EVM linear output.