Transformer matched gilbert mixer with active balun for D band transmitter

Abstract

A Gilbert mixer for the application of a D band transmitter is presented. In the work, the differential pair below the mixing quad is replaced by an active balun. A source resistor is introduced to improve balance performance of the active balun. Owing to the resistor, the LO‐to RF isolation of the mixer is also improved. At the output end, a transformer‐based balun is used to transform differential signal to single‐end signal and realize wideband output match. The circuit is designed on a 130 nm SiGe BiCMOS technology with fT/fmax of 300/500 GHz. The compact mixer covers 5 GHz intermediate frequency (IF) tuning range (1 to 6 GHz) with LO frequency fixed at 150 GHz. The measured RF 3‐dB bandwidth varying from 128 to 160 GHz with maximum −6 dB conversion gain, when the LO frequency is tuned. And the output referred 1‐dB compression point (OP1dB) is nearly −15 dBm. The mixer except test circuit consumes 14 mW DC power.

Recent advancement in the design of mixers for software‐defined radios

“…95 Yu et al employed a transformer is at the output end for differential to single-ended signal conversion for wideband matching. 96 The design also employs coupling capacitors for amplitude and phase matching of the transformer. Likewise, Hermann et al employed an on-chip resonating transformer to attain high current gain.…”