A Broadband Dual-Polarized Terahertz Direct Detector in a 0.13-μm SiGe HBT Technology

This paper presents a dual-polarized terahertz (THz) direct detector with an integrated, differential wire-ring antenna, coupled to an external silicon lens. It is implemented in an advanced 0.13-μm SiGe HBT technology with f T /f max of 350/550 GHz. It comprises two pairs of differentially driven HBT transistors in common-base (CB) configuration. Their voltage-mode readout is characterized in the forward-active and in the saturation region with an external load resistance of 1.83 kΩ. In the forward-active region the detector’s optical noise equivalent power (NEP) is lower than $38{\text{pW/}}\sqrt {{\text{Hz}}} $ in the measured 220-1000 GHz band. Best NEP values of 2.7 to $3.4{\text{pW/}}\sqrt {{\text{Hz}}} $ were measured in the frequency range of 430 to 476 GHz, corresponding to a voltage responsivity of 5 ± 0.6 kV/W. In the saturation region the minimum NEP with no collector biasing is $8.2{\text{pW/}}\sqrt {{\text{Hz}}} $. This is the first reported silicon-integrated SiGe HBT THz direct detector, operating at room temperature, with an NEP below $10{\text{pW/}}\sqrt {{\text{Hz}}} $ in the frequency range between 300 GHz and 500 GHz.