Broadband Sensing Around 1 THz Via a Novel Biquad-Antenna-Coupled Low-NEP Detector in CMOS
M. Ferreras1, D. Cibiraite-Lukenskiene2, A. Lisauskas3,4, J. Grajal1, and V. Krozer1,5
Published in:
IEEE Trans. Terahertz Sci. Technol., vol. 11, no. 1, pp. 16-27 (2021).
Abstract:
We report on the design and characterization of a novel backside-radiating antenna-coupled direct terahertz detector fabricated in 65 nm CMOS technology. The novelty of the design lies in the low-metal coverage of the biquad antenna geometry, which adapts well to the particular challenging conditions of on-chip antenna integration in silicon and allows optimization for a versatility of operation conditions. The biquad antenna was modified here to achieve wideband radiation and matching to a gate-coupled single-finger field-effect transistor with ac open condition at the drain terminal. The successful detector performance was the result of a careful treatment of transistor, antenna, and optics from a codesign perspective, since the beginning of the design. This included the frequency-dependent complex impedance for optimum matching, the technology restrictions to ensure proper chip fabrication, and the overall detection efficiency after backing the device with a silicon lens. Calibrated detector measurements for 7777 Hz modulation frequency yielded minimum optical noise-equivalent-power (NEP) of 25 pW/√Hz at 1 THz, with NEP values below 50 pW/√Hz in the 0.84-1.29 THz frequency range. These figures achieve state-of-the-art of wideband CMOS-based detectors and are only a factor of ∼2 inferior to the best reported narrowband devices close to 1 THz.
1 Information Processing and Telecommunications Center, Universidad Politécnica de Madrid, 28040 Madrid, Spain
2 Terahertz Photonics Group, Physikalisches Institut, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
3 Institute of Applied Electrodynamics and Telecommunications, Vilnius University, LT-10257 Vilnius, Lithuania
4 CENTERA Laboratories, Institute of High Pressure Physics PAS, PL-01-142 Warsaw, Poland
5 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, D-12489 Berlin, Germany
Index Terms:
CMOS integrated circuit, on-chip antenna, TeraFET, terahertz (THz) power detector, wideband terahertz sensor.
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