Influence of Amplitude and Phase Imbalance on a Y-band Bootstrapped Frequency Doubler using 130-nm SiGe Technology

This paper presents a fully-differential bootstrapped Gilbert-cell-based frequency doubler designed in a 130-nm SiGe process to provide an output frequency of 220 GHz. At this frequency, an underlying asymmetrical layout of the switching quad leads to several problems such as output amplitude difference, phase difference deviating from 180°, and conversion gain (CG) degradation. An imbalance analysis is therefore carried out to understand the critical layout routings. The results show that the imbalance at the collectors of the transistors has the most severe impact on the differential output amplitudes and phases. On the other hand, imbalance at the base influences the CG mostly. Based on these findings, a frequency doubler was designed in the SiGe SG13G2 technology. The proposed frequency doubler achieves a maximum output power of -5.8dBm and a 1-dB bandwidth of 25 GHz from 202.5 GHz to 227.5 GHz with 91 mW of dc power consumption in the full EM post layout simulation.