{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T14:50:19Z","timestamp":1777042219820,"version":"3.51.4"},"reference-count":25,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2016,3,3]],"date-time":"2016-03-03T00:00:00Z","timestamp":1456963200000},"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 first low noise complementary metal oxide semiconductor (CMOS) terahertz (THz) imager based on source modulation and in-pixel high-Q filtering. The                                        31               \u00d7               31                                  focal plane array has been fully integrated in a                                        0               .               13                              \u03bc                                 m standard CMOS process. The sensitivity has been improved significantly by modulating the active THz source that lights the scene and performing on-chip high-Q filtering. Each pixel encompass a broadband bow tie antenna coupled to an N-type metal-oxide-semiconductor (NMOS) detector that shifts the THz radiation, a low noise adjustable gain amplifier and a high-Q filter centered at the modulation frequency. The filter is based on a passive switched-capacitor (SC) N-path filter combined with a continuous-time broad-band Gm-C filter. A simplified analysis that helps in designing and tuning the passive SC N-path filter is provided. The characterization of the readout chain shows that a Q factor of 100 has been achieved for the filter with a good matching between the analytical calculation and the measurement results. An input-referred noise of                                        0               .               2                              \u03bc                                 V RMS has been measured. Characterization of the chip with different THz wavelengths confirms the broadband feature of the antenna and shows that this THz imager reaches a total noise equivalent power of                                        0               .               6                                  nW at 270 GHz and                                        0               .               8                                  nW at 600 GHz.<\/jats:p>","DOI":"10.3390\/s16030325","type":"journal-article","created":{"date-parts":[[2016,3,3]],"date-time":"2016-03-03T10:30:47Z","timestamp":1457001047000},"page":"325","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":45,"title":["A Low-Noise CMOS THz Imager Based on Source Modulation and an In-Pixel High-Q Passive Switched-Capacitor N-Path Filter"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0506-7648","authenticated-orcid":false,"given":"Assim","family":"Boukhayma","sequence":"first","affiliation":[{"name":"Univ. Grenoble Alpes, CEA, LETI, MINATEC Campus, Grenoble F-38054, France"},{"name":"ICLAB, EPFL, Rue de la Maladi\u00e8re 71, Neuch\u00e2tel 2000, Switzerland"}]},{"given":"Antoine","family":"Dupret","sequence":"additional","affiliation":[{"name":"Univ. Grenoble Alpes, CEA, LETI, MINATEC Campus, Grenoble F-38054, France"}]},{"given":"Jean-Pierre","family":"Rostaing","sequence":"additional","affiliation":[{"name":"Univ. Grenoble Alpes, CEA, LETI, MINATEC Campus, Grenoble F-38054, France"}]},{"given":"Christian","family":"Enz","sequence":"additional","affiliation":[{"name":"ICLAB, EPFL, Rue de la Maladi\u00e8re 71, Neuch\u00e2tel 2000, Switzerland"}]}],"member":"1968","published-online":{"date-parts":[[2016,3,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1514","DOI":"10.1109\/JPROC.2007.898903","article-title":"Terahertz Spectroscopy and Imaging for Defense and Security Applications","volume":"95","author":"Liu","year":"2007","journal-title":"IEEE Proc."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"810","DOI":"10.1109\/TTHZ.2015.2460671","article-title":"Non-Destructive Evaluation of Polymer Composite Materials at the Manufacturing Stage Using Terahertz Pulsed Spectroscopy","volume":"5","author":"Yakovlev","year":"2015","journal-title":"IEEE Trans. Terahertz Sci. Technol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1109\/TTHZ.2011.2159551","article-title":"THz Medical Imaging: in vivo Hydration Sensing","volume":"1","author":"Taylor","year":"2011","journal-title":"IEEE Trans. Terahertz Sci. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3768","DOI":"10.1109\/JLT.2014.2314139","article-title":"Quantitative Mapping of Pharmaceutical Cocrystals within Cellulose by Terahertz Spectroscopy","volume":"32","author":"Kim","year":"2014","journal-title":"J. Lightwave Technol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"9973","DOI":"10.3390\/s111009973","article-title":"Application of Terahertz Radiation to Soil Measurements: Initial Results","volume":"11","author":"Dworak","year":"2011","journal-title":"Sensors"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Han, S.T., Park, W.K., and Chun, H.S. (2011, January 2\u20137). Development of Sub-THz gyrotron for real-time food inspection. Proceedings of the 36th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz), Rome, Italy.","DOI":"10.1109\/irmmw-THz.2011.6105104"},{"key":"ref_7","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_8","doi-asserted-by":"crossref","first-page":"961","DOI":"10.1007\/s10762-015-0197-x","article-title":"Terahertz Real-Time Imaging Uncooled Arrays Based on Antenna-Coupled Bolometers or FET Developed at CEA-Leti","volume":"36","author":"Simoens","year":"2015","journal-title":"J. Infrared Millim. Terahertz Waves"},{"key":"ref_9","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_10","doi-asserted-by":"crossref","unstructured":"Schuster, F., Videlier, H., Dupret, A., Coquillat, D., Sakowicz, M., Rostaing, J., Tchagaspanian, M., Giffard, B., and Knap, W. (2011, January 20\u201324). A broadband THz imager in a low-cost CMOS technology. Proceedings of the 2011 IEEE International Solid-State Circuits Conference Digest of Technical Papers (ISSCC), San Francisco, CA, USA.","DOI":"10.1109\/ISSCC.2011.5746211"},{"key":"ref_11","unstructured":"Kim, D.Y., Park, S., Han, R., and Kenneth, K. (2013, January 11\u201314). 820-GHz imaging array using diode-connected NMOS transistors in 130-nm CMOS. Proceedins of the 2013 Symposium on VLSI Circuits (VLSIC), Kyoto, Japan."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"2999","DOI":"10.1109\/JSSC.2012.2217851","article-title":"A 1 k-Pixel Video Camera for 0.7-1.1 Terahertz Imaging Applications in 65-nm CMOS","volume":"47","author":"Sherry","year":"2012","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"998","DOI":"10.1109\/JSSC.2011.2117010","article-title":"Tunable High-Q N-Path Band-Pass Filters: Modeling and Verification","volume":"46","author":"Ghaffari","year":"2011","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Boukhayma, A., Rostaing, J.P., Mollard, A., Guellec, F., Benetti, M., Ducournau, G., Lampin, J.F., Dupret, A., Enz, C., and Tchagaspanian, M. (2014, January 22\u201326). A 533pW NEP 31 \u00d7 31 pixel THz image sensor based on in-pixel demodulation. Proceedings of the European Solid State Circuits Conference (ESSCIRC), ESSCIRC 2014\u201440th, Venice, Italy.","DOI":"10.1109\/ESSCIRC.2014.6942082"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"380","DOI":"10.1109\/16.485650","article-title":"Detection, mixing, and frequency multiplication of terahertz radiation by two-dimensional electronic fluid","volume":"43","author":"Dyakonov","year":"1996","journal-title":"IEEE Trans. Electron. Devices"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2465","DOI":"10.1103\/PhysRevLett.71.2465","article-title":"Shallow water analogy for a ballistic field effect transistor: New mechanism of plasma wave generation by dc current","volume":"71","author":"Dyakonov","year":"1993","journal-title":"Phys. Rev. Lett."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Lisauskas, A., Pfeiffer, U., \u00c3\u0170jefors, E., Bol\u00c3\u0148var, P.H., Glaab, D., and Roskos, H.G. (2009). Rational design of high-responsivity detectors of terahertz radiation based on distributed self-mixing in silicon field-effect transistors. J. Appl. Phys., 105.","DOI":"10.1063\/1.3140611"},{"key":"ref_18","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":"Ojefors","year":"2009","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"9346","DOI":"10.1063\/1.1468257","article-title":"Nonresonant detection of terahertz radiation in field effect transistors","volume":"91","author":"Knap","year":"2002","journal-title":"J. Appl. Phys."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1584","DOI":"10.1109\/5.542410","article-title":"Circuit techniques for reducing the effects of op-amp imperfections: Autozeroing, correlated double sampling, and chopper stabilization","volume":"84","author":"Enz","year":"1996","journal-title":"Proc. IEEE"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"7827","DOI":"10.1364\/OE.19.007827","article-title":"Broadband terahertz imaging with highly sensitive silicon CMOS detectors","volume":"19","author":"Schuster","year":"2011","journal-title":"Opt. Express"},{"key":"ref_22","unstructured":"Thomas, R., and Jenkins, M. (1980). Analog Switches and Their Applications, Siliconix."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"750","DOI":"10.1109\/4.315","article-title":"A 4-MHz CMOS continuous-time filter with on-chip automatic tuning","volume":"23","author":"Krummenacher","year":"1988","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"753","DOI":"10.1109\/JSSC.1983.1052027","article-title":"An integrated CMOS switched-capacitor bandpass filter based on N-path and frequency-sampling principles","volume":"18","author":"Sigg","year":"1983","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2962","DOI":"10.1109\/JSSC.2013.2285852","article-title":"Design of Active N-Path Filters","volume":"48","author":"Darvishi","year":"2013","journal-title":"IEEE J. Solid State Circuits"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/3\/325\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:20:07Z","timestamp":1760210407000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/3\/325"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,3,3]]},"references-count":25,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2016,3]]}},"alternative-id":["s16030325"],"URL":"https:\/\/doi.org\/10.3390\/s16030325","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,3,3]]}}}