SiGe receiver front ends and flip-chip integrated wideband antennas for millimeter-wave passive imaging

Abstract

SiGe wideband 77-GHz and 94-GHz front end receivers with integrated antennas for passive imaging have been designed and characterized. These front end systems exhibit wideband performance with the highest gain and lowest noise figures reported thus far for silicon-based systems in the 77-GHz and 94-GHz frequency regimes, to the best of the author's knowledge. These systems each comprise a fully differential integrated antenna, LNA, and a double-balanced mixer. A separate 77-GHz front end also features an on-chip 72-GHz cross-coupled VCO. The 77-GHz front end receiver achieves 46 dB max conversion gain, 6.5-10 dB noise figure (NF), output-referred 1dB compression point of +2 dBm and DC power dissipation (PDc) of 122 mW. The 94-GHz receiver achieves 47 dB max conversion gain, 7-12.5 dB NF, and PDC of 120 mW. The antenna performance yields gains of 10-13 dB over 70-100 GHz, with greater than 90% efficiency. The integrated antenna exhibits a typical loss of 0.5-1 dB, or 80-90% efficiency, and a worst-case radiation loss of _ -2 dB (efficiency = 63%). These reported results exceed published on-chip antenna performance, which typically achieve < 10% efficiency. Antenna loss degrades receiver noise figure and gain, yielding a less viable receiver. The individual design, co-design and integration of each element making up the RF front end collectively contribute to the overall high performance of these front end receivers. The 77-GHz LNA achieves 4.9-6.0 dB NF, 18-26 dB gain, and S11, S22 of -13.0 and -12.8 dB, respectively. The mixer achieves 12-14 dB NF, 20-26 dB conversion gain and -26dBm IP1dB (input-referred). The VCO achieves output power from -2 to 0 dBm with phase noise of -93 dBc/Hz at 72 GHz. The 94-GHz LNA achieves 22-dB max gain, 7.0 dB NF, -25 dB and -10 dB S11 and S22, respectively. This LNA also exhibits very wideband performance, achieving >10 dB gain from 40-100 GHz.