Design and fabrication of a terahertz imaging circuit in CMOS process technology

Abstract

Using terahertz waves for imaging is gaining increased interest. A CMOS cascode amplifier biased near the threshold voltage of a MOSFET for terahertz direct detection is proposed. A CMOS terahertz imaging circuit is designed and fabricated on the basis of a low-cost 180-nm CMOS process technology. The imaging circuit consists of a microstrip patch antenna, an impedance-matching circuit, and the direct detector. The imaging circuit achieve a responsivity of 51.9 kV/W at 0.915 THz and noise equivalent power (NEP) of 358 pW/Hz1/2 at modulation frequency of 31 Hz. NEP is estimated to be reduced to 33.5 pW/Hz1/2 at 10 kHz. The imaging circuit occupies 250 × 180 m. These results suggest that cost-efficient terahertz imaging is possible in the near future.