A 26dB-gain 100GHz Si/SiGe Cascaded Constructive-Wave Amplifier

An amplifier topology - the cascaded constructive-wave amplifier (CCWA) - that combines features of traveling-wave and cascaded amplifiers for millimeter-wave applications is presented. The circuit is implemented in 0.12 mum SiGe BiCMOS. The HBT devices have f
_t
of 200GHz. The chip measures 330x1000 mum
²
including the pads. The area of a single stage measures 160times60 mum
²
. Within a single stage, the shielded coplanar transmission line meanders through a length of 220 mum. This structure is area efficient and minimizes the distance between the input and output of the stage. In conclusion, the CCWA topology is based on cascaded traveling-wave stages that offer wideband gain previously unachievable in silicon technologies. The 26 dB amplifier provides 7 dB more gain than recent W-band work in 0.12 mum SiGe.