{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,2]],"date-time":"2026-01-02T07:45:51Z","timestamp":1767339951859,"version":"build-2065373602"},"reference-count":36,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2018,6,7]],"date-time":"2018-06-07T00:00:00Z","timestamp":1528329600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper presents the design, implementation and characterization results of a pixel-level readout chain integrated with a FET-based terahertz (THz) detector for imaging applications. The readout chain is fabricated in a standard 150-nm CMOS technology and contains a cascade of a preamplification and noise reduction stage based on a parametric chopper amplifier and a direct analog-to-digital conversion by means of an incremental \u03a3\u0394 converter, performing a lock-in operation with modulated sources. The FET detector is integrated with an on-chip antenna operating in the frequency range of 325\u2013375 GHz and compliant with all process design rules. The cascade of the FET THz detector and readout chain is evaluated in terms of responsivity and Noise Equivalent Power (NEP) measurements. The measured readout input-referred noise of 1.6 \u03bc V r m s allows preserving the FET detector sensitivity by achieving a minimum NEP of 376 pW\/ Hz in the optimum bias condition, while directly providing a digital output. The integrated readout chain features 65-dB peak-SNR and 80-\u03bc W power consumption from a 1.8-V supply. The area of the antenna-coupled FET detector and the readout chain fits a pixel pitch of 455 \u03bcm, which is suitable for pixel array implementation. The proposed THz pixel has been successfully applied for imaging of concealed objects in a paper envelope under continuous-wave illumination.<\/jats:p>","DOI":"10.3390\/s18061867","type":"journal-article","created":{"date-parts":[[2018,6,8]],"date-time":"2018-06-08T03:13:18Z","timestamp":1528427598000},"page":"1867","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["A Low-Noise Direct Incremental A\/D Converter for FET-Based THz Imaging Detectors"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4211-2417","authenticated-orcid":false,"given":"Moustafa","family":"Khatib","sequence":"first","affiliation":[{"name":"Center for Materials and Microsystems, Integrated Radiation and Image Sensors Group, Fondazione Bruno Kessler, Trento 38122, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8777-1593","authenticated-orcid":false,"given":"Matteo","family":"Perenzoni","sequence":"additional","affiliation":[{"name":"Center for Materials and Microsystems, Integrated Radiation and Image Sensors Group, Fondazione Bruno Kessler, Trento 38122, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2018,6,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"E48","DOI":"10.1364\/AO.49.000E48","article-title":"Terahertz imaging: applications and perspectives","volume":"10","author":"Jansen","year":"2010","journal-title":"Appl. Opt."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"910","DOI":"10.1109\/22.989974","article-title":"Terahertz technology","volume":"50","author":"Siege","year":"2002","journal-title":"IEEE Trans. Microw. Theory Technol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"S266","DOI":"10.1088\/0268-1242\/20\/7\/018","article-title":"THz imaging and sensing for security applications\u2013explosives, weapons and drugs","volume":"20","author":"Federici","year":"2011","journal-title":"Semicond. Sci. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1109\/TTHZ.2011.2159562","article-title":"THz chemical imaging for biological applications","volume":"1","author":"Ajito","year":"2011","journal-title":"IEEE Trans. Terahertz Sci. Technol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1016\/j.tifs.2011.12.006","article-title":"Terahertz time domain spectroscopy and imaging: emerging techniques for food process monitoring and quality control","volume":"25","author":"Gowen","year":"2012","journal-title":"Trends Food Sci. Technol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"547","DOI":"10.1007\/s10762-006-9106-7","article-title":"Terahertz quality control of polymeric products","volume":"27","author":"Rutz","year":"2007","journal-title":"Int. J. Infrared Millim. Waves"},{"key":"ref_7","first-page":"395","article-title":"Terahertz imaging for nondestructive evaluation of packaged power electronic devices","volume":"4","author":"Burford","year":"2014","journal-title":"Int. J. Emerg. Technol. Adv. Eng."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1109\/TTHZ.2011.2159559","article-title":"THz active imaging systems with real-time capabilities","volume":"1","author":"Friederich","year":"2011","journal-title":"IEEE Trans. Terahertz Sci. Technol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4817","DOI":"10.1364\/OE.21.004817","article-title":"Imaging of broadband terahertz beams using an array of antenna-coupled microbolometers operating at room temperature","volume":"21","author":"Oden","year":"2013","journal-title":"Opt. Express"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2296","DOI":"10.1109\/JSSC.2013.2269856","article-title":"Active terahertz imaging using Schottky diodes in CMOS: Array and 860-GHz pixel","volume":"48","author":"Han","year":"2013","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1007\/s10762-013-0047-7","article-title":"Exploration of terahertz imaging with silicon MOSFETs","volume":"35","author":"Lisauskas","year":"2014","journal-title":"Int. J. Infrared Millim. Terahertz Waves"},{"key":"ref_12","first-page":"1968","article-title":"280-GHz Schottky diode detector in 130-nm digital CMOS","volume":"46","author":"Han","year":"2010","journal-title":"Proc. IEEE Custom Integr. Circuits"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1968","DOI":"10.1109\/JSSC.2009.2021911","article-title":"A 0.65 THz focal-plane array in a quarter-micron CMOS process technology","volume":"44","author":"Pfeiffer","year":"2009","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2999","DOI":"10.1109\/JSSC.2012.2217851","article-title":"A 1 k-Pixel video camera for 0.7\u20131.1 terahertz Imaging applications in 65-nm CMOS","volume":"47","author":"Sherry","year":"2012","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Boukhayma, A., Dupret, A., Rostaing, J.P., and Enz, C. (2016). A low-noise CMOS THz imager based on source modulation and an in-pixel high-Q passive switched-capacitor N-path filter. Sensors, 16.","DOI":"10.3390\/s16030325"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"455","DOI":"10.1109\/TTHZ.2017.2692040","article-title":"CMOS Fully Integrated 860-GHz Terahertz Sensor","volume":"7","author":"Liu","year":"2017","journal-title":"IEEE Trans. Terahertz Sci. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Khatib, M., Perenzoni, M., and Stoppa, D. (2017, January 11\u201314). A noise-efficient, in-pixel readout for FET-based THz detectors with direct incremental A\/D conversion. Proceedings of the 43rd IEEE European Solid State Circuits Conference, Leuven, Belgium.","DOI":"10.1109\/ESSCIRC.2017.8094516"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Khatib, M., Perenzoni, M., and Stoppa, D. (2016, January 25\u201330). A CMOS 0.15-\u03bcm in-pixel noise reduction technique for readout of antenna-coupled FET-based THz detectors. Proceedings of the 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz), Copenhagen, Denmark.","DOI":"10.1109\/IRMMW-THz.2016.7758741"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"253511","DOI":"10.1063\/1.2410215","article-title":"Plasma wave detection of terahertz radiation by silicon field effects transistors: responsivity and noise equivalent power","volume":"89","author":"Tauk","year":"2006","journal-title":"Appl. Phys. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"114511","DOI":"10.1063\/1.3140611","article-title":"Rational design of high-responsivity detectors of terahertz radiation based on distributed self-mixing in silicon field-effect transistors","volume":"105","author":"Lisauskas","year":"2009","journal-title":"J. Appl. Phys."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Grzyb, J., Sherry, H., Cathelin, A., Kaiser, A., and Pfeiffer, U.R. (2012, January 23\u201328). On the co-design between on-chip antennas and THz MOSFET direct detectors in CMOS technology. Proceedings of the 2012 37th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), Wollongong, NSW, Australia.","DOI":"10.1109\/IRMMW-THz.2012.6380197"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"3834","DOI":"10.1109\/TMTT.2012.2221732","article-title":"CMOS integrated antenna-coupled field-effect-transistors for the detection of radiation from 0.2 to 4.3 THz","volume":"60","author":"Boppel","year":"2012","journal-title":"IEEE Trans. Microw. Theory Technol."},{"key":"ref_23","unstructured":"Perenzoni, M., and Cavallo, D. (2015, January 13\u201317). Design of an efficient 900 GHz antenna in standard CMOS technology for imaging arrays. Proceedings of the 2015 9th European Conference on Antennas and Propagation (EuCAP), Lisbon, Portugal."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Ranganathan, S., and Tsividis, Y. (2003, January 13). A MOS capacitor-based discrete-time parametric amplifier with 1.2 V output swing and 3 nW power dissipation. Proceedings of the 2003 IEEE International Solid-State Circuits Conference, San Francisco, CA, USA.","DOI":"10.1109\/ISSCC.2003.1234357"},{"key":"ref_25","unstructured":"Tsividis, Y., and Suyama, K. (1997, January 12). Strange ways to use the MOSFET. Proceedings of the 1997 IEEE International Symposium on Circuits and Systems, Hong Kong."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1489","DOI":"10.1109\/TCSI.2015.2418892","article-title":"A power-efficient continuous-time incremental sigma-delta ADC for neural recording systems","volume":"62","author":"Tao","year":"2015","journal-title":"IEEE Trans. Circuits Syst. I Regul. Pap."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"678","DOI":"10.1109\/TCSI.2004.826202","article-title":"Theory and applications of incremental \u0394\u03a3 converters","volume":"51","author":"Markus","year":"2004","journal-title":"IEEE Trans. Circuits Syst. I Regul. Pap."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Liang, J., and Johns, D.A. (June, January 30). A frequency-scalable 15-bit incremental ADC for low power sensor applications. Proceedings of the 2010 IEEE International Symposium on Circuits and Systems (ISCAS), Paris, France.","DOI":"10.1109\/ISCAS.2010.5537172"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Khatib, M., and Perenzoni, M. (2016, January 3\u20137). Pixel-level continuous-time incremental sigma-delta A\/D converter for THz sensors. Proceedings of the Optical Sensing and Detection IV, Brussels, Belgium.","DOI":"10.1117\/12.2220463"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"859","DOI":"10.1109\/4.78275","article-title":"An adaptive analog continuous-time CMOS biquadratic filter","volume":"26","author":"Kwan","year":"1991","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1234","DOI":"10.1109\/4.261997","article-title":"A BiCMOS low-distortion 8 MHz low-pass filter","volume":"28","author":"Willingham","year":"1993","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_32","unstructured":"Allen, P.E., and Holberg, D.R. (2002). CMOS Analog Circuit Design, Oxford University Press. [2nd ed.]."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1109\/JSSC.1987.1052730","article-title":"A CMOS chopper amplifier","volume":"22","author":"Enz","year":"1987","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1225","DOI":"10.1109\/TIM.2016.2534199","article-title":"A methodology to measure input power and effective area for characterization of direct THz detectors","volume":"65","author":"Ali","year":"2016","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"054512","DOI":"10.1063\/1.3632058","article-title":"Terahertz responsivity of field effect transistors versus their static channel conductivity and loading effects","volume":"110","author":"Sakowicz","year":"2011","journal-title":"J. Appl. Phys."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"203504","DOI":"10.1063\/1.4717464","article-title":"Terahertz current oscillations in a gated two-dimensional electron gas with antenna integrated at the channel ends","volume":"100","author":"Casini","year":"2012","journal-title":"Appl. Phys. Lett."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/6\/1867\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:07:43Z","timestamp":1760195263000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/6\/1867"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,6,7]]},"references-count":36,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2018,6]]}},"alternative-id":["s18061867"],"URL":"https:\/\/doi.org\/10.3390\/s18061867","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2018,6,7]]}}}