Design and Fabrication of Terahertz Detectors Based on 180-Nm CMOS Process Technology

A CMOS cascode amplifier, biased near the threshold voltage of a MOSFET, for terahertz direct detection is proposed. A CMOS terahertz imaging circuit (size: 250 × 180 ìm) is designed and fabricated on the basis of low-cost 180-nm CMOS process technology. The imaging circuit consists of a microstrip patch antenna, an impedance-matching circuit, and a direct detector. It achieves a responsivity of 51.9 kV/W at 0.915 THz and a noise equivalent power (NEP) of 358 pW/Hz1/2 at a modulation frequency of 31 Hz. NEP is estimated to be reduced to 42 pW/Hz1/2 at 100 kHz. These results suggest that cost-efficient terahertz imaging is possible in the near future.