Implementation of high-coupling and broadband transformer in RFCMOS technology

This paper proposes a structure for transformer with high-coupling, broadband, and small chip area characteristics using current silicon-based technology. The proposed device has tight coupling (k=0.92), wide bandwidth (f_SR=30.8 GHz), and minimum chip area (OD=140 μm). Furthermore, the analytical formula for calculating mutual inductance is derived in this study; experimental results indicate that the analytical formula is feasible. The proposed transformer will be useful in designing high-performance RF integrated circuits for wireless applications.