A novel transformer-based mm-Wave frequency doubler with enhanced output symmetry

A novel transformer-based differential frequency doubler operating in mm-Wave range is presented in this paper. The differential output signal is generated by the second harmonic of the nonlinear push-push pairs. In order to enhance the symmetry of the high frequency differential output, a stacked transformer implemented by the top two metal layers in 90-nm CMOS process is used as the loads in the proposed frequency doubler. Simulation results show that the proposed circuit has achieved less than 1∘\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1^{\circ }$$\end{document} phase mismatch and 0.6-dB amplitude mismatch operating at 60-GHz.