Triple-Band Antenna-Coupled Terahertz Direct Detectors in a 0.13-µm SiGe HBT Technology

This paper presents differential terahertz (THz) direct detectors coupled to an integrated, triple-band antenna implemented in a 0.13-µm SiGe HBT technology with f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf>/f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> of 250/370 GHz. It comprises three pairs of differentially driven HBT transistors in common-base (CB) configuration, each individually read out in the voltage mode with an external load resistance of 1.8 kΩ. Each detector pair corresponds to a different frequency band, covering the frequency ranges from 200 GHz to 350 GHz, 350 GHz to 450 GHz, and 550 GHz to 1000 GHz. The minimum optical noise equivalent power (NEP) characterized by free-space measurements is lower than 72 ${\text{pW}}/\sqrt {{\text{Hz}}} $ in the measured 200 GHz to 350 GHz band, 400 ${\text{pW}}/\sqrt {{\text{Hz}}} $ in the 350 GHz to 450 GHz band and 100 ${\text{pW}}/\sqrt {{\text{Hz}}} $ in the 550 GHz to 1000 GHz frequency band. Best NEP values of 14 ${\text{pW}}/\sqrt {{\text{Hz}}} $ at 298 GHz, 143 ${\text{pW}}/\sqrt {{\text{Hz}}} $ at 430 GHz and 35 ${\text{pW}}/\sqrt {{\text{Hz}}} $ at 627 GHz were measured with corresponding maximum voltage responsivities of 1.8 kV/W, 0.17 kV/W and 0.72 kV/W, respectively.