Ultra-broadband 0.18-µm BiCMOS active baluns for extremely wideband RF applications

A new RF active balun is proposed, analyzed and designed using a 0.18-μm BiCMOS technology, showing its distinguished characteristic of good balance across ultra-wide frequency ranges. The active balun provides a high differential-mode gain and extremely low common-mode gain; hence, ultra-high common-mode signal suppression. The designed 0.18-μm BiCMOS active balun exhibits an ultra-broadband performance from 2 to 40 GHz differential-mode gain from 1 to 5.2 dB and common-mode signal suppression from 25 to 71 dB. Good matching at its input and output are obtained at the 35-GHz design frequency. The RF active balun consumes a dc current of 8.2 mA from a 1.8 V source.