68-73 GHz Common-Base HBT Amplifier in 55 nm SiGe Technology

The design of a common-base (CB), power-combined, SiGe BiCMOS amplifier is reported. Wilkinson couplers are used for power splitting and combining at the input and output of the amplifier. The HBTs have three emitter fingers and each finger has a length of 2.7 mu m and a width of 0.18 mu m. The gain of the amplifier can be externally varied by biasing the HBTs from a 1.3-1.5 V dc supply applied to their collectors through on-chip bias tees and applying 850-900mV to the bases. Measurements on the fabricated amplifier reveal that the maximum gain can be varied between 10.91 and 15.75 dB, it has a 3-dB bandwidth from 68 to 73 GHz and an OP1dB of -1.8 dBm at 71 GHz. The chip area is 0.8 mm(2) and it draws a dc power between 5.2 and 18.7 mW.