SiGe power devices for 802.11a wireless LAN applications at 5 GHz

The feasibility of SiGe heterojunction bipolar transistors (HBTs) for 802.11a wireless LAN power amplifier applications in the 5 GHz regime is demonstrated. The device layout is optimised using unit power devices to develop high-power HBTs. SiGe HBTs with an emitter area of 1152 μm² achieve a maximum output power of 25 dBm and PAE of 36% at 5.35 GHz under a supply voltage of 3.0 V. The measured ACPR for this device under OFDM modulated signal is -23 and -32 dBc at 10 and 20 MHz offset, respectively, at an output power backed off by 9 dB from P_1dB.