High efficiency millimeter-wave stacked two turn transformer using only top two thick metals

A new high efficiency stacked millimeter-wave transformer is designed and fabricated in 0.18 μm CMOS technology using dual thick metal stack. The proposed configuration allows efficient implementation of two turn stacked transformers, exclusively using top two thick metal layers. Measurements show significant improvements in efficiency, coupling coefficient and current handling when compared to existing two turn stacked transformer configurations. Using the top thick metals substantially increases the current handling while reducing the capacitance to substrate. Further, the proposed transformer exhibits perfect symmetry across both primary and secondary and can be readily converted to a balun.