Low-NEP Room-Temperature Broadband THz Direct Detection with a 0.13-μm SiGe HBT Device

This paper reports on the influence of internal device parasitics of a high-speed SiGe HBT, its bias operation range, and circuit-antenna co-design aspects on frequency-dependent rectification efficiency of the room-temperature operated antenna-coupled THz direct detectors in 130-nm technology leading to their low-NEP operation in a near-THz fractional bandwidth. In particular, an optical NEP below 36 pW/√Hz was measured across 220–1000 GHz for the single and dual linearly-polarized detectors with minimum NEP values of 1.9 pW/√Hz at 292 GHz and 2.7 pW/√Hz at 449 GHz for the former and the latter, respectively.