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CMOS circuits for terahertz imaging
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Paper Abstract

Terahertz (THz) electronics using mainstream CMOS technologies can be a small, low-cost alternative to discretecomponent THz systems. Due to high yield and integration level, large-scale THz imaging systems can be affordably realized in a small form factor. In this paper, state-of-the-art CMOS circuits for THz imaging are reviewed. Incoherent detectors in CMOS process offer comparable noise equivalent power (NEP) to III-V counterparts at a fraction of the cost. An 820-GHz 8×8 array with minimum NEP of 12.6pW/√Hz is demonstrated using diode-connected MOSFET’s in 130- nm CMOS. Schottky-barrier diodes (SBD’s) fabricated using a 130-nm CMOS process demonstrate higher cutoff frequency than MOSFET’s. Using the SBD, detection at 9.7THz is demonstrated. The same SBD’s are also used to implement a 218-GHz 6×6 detector array for a THz camera module. Mixer-based coherent detectors show orders-ofmagnitude better sensitivity than that of incoherent detectors. Mixers require a local oscillator (LO) signal. The design challenge of including an LO can be relaxed by using a sub-harmonic mixing technique. A 410-GHz 4th order subharmonic mixer requires −1.6-dBm LO power at 102.5GHz and shows 44-dB better sensitivity than incoherent detectors operating near 400GHz. LO’s can be directly integrated with the mixing device to form a compact transceiver. A 260-GHz transceiver that integrates a VCO, antenna and mixer, occupies only 480×580μm2 and shows a 13.5-dB better sensitivity at 260 GHz than the incoherent detector with the lowest NEP. Since the area is less than λ/2×λ/2, it should be possible to build large-scale focal plane arrays with coherent detectors and transmitters.

Paper Details

Date Published: 13 May 2019
PDF: 10 pages
Proc. SPIE 10982, Micro- and Nanotechnology Sensors, Systems, and Applications XI, 1098231 (13 May 2019); doi: 10.1117/12.2518654
Show Author Affiliations
Wooyeol Choi, Oklahoma State Univ. (United States)
The Univ. of Texas at Dallas (United States)
Dae-Yeon Kim, Qorvo, Inc. (United States)
Zeshan Ahmad, Texas Instruments Inc. (United States)
Pranith R. Byreddy, The Univ. of Texas at Dallas (United States)
Yukun Zhu, The Univ. of Texas at Dallas (United States)
Jensen Newman, The Univ. of Texas at Dallas (United States)
Kenneth K. O, The Univ. of Texas at Dallas (United States)


Published in SPIE Proceedings Vol. 10982:
Micro- and Nanotechnology Sensors, Systems, and Applications XI
Thomas George; M. Saif Islam, Editor(s)

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