{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/118025"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/118025","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Wideband and fast THz spectrometer using dual-frequency-comb on CMOS","abstract":"Millimeter-wave/terahertz rotational spectroscopy of polar gaseous molecules provides a powerful tool for complicated gas mixture analysis. Here, a 220-to-320 GHz dual-frequency-comb spectrometer in 65-nm bulk CMOS is presented, along with a systematic analysis on fundamental issues of rotational spectrometer, including the impacts of various noise mechanisms, gas cell, molecular properties, detection sensitivity, etc. The spectrometer utilizes two counter-propagating frequency-comb signals to seamlessly scan the broadband spectrum. The comb signal, with 10 equally-spaced frequency tones, is generated and detected by a chain of inter-locked transceivers on chip. Each transceiver is based on a multi-functional electromagnetic structure, which serves as frequency doubler, sub-harmonic mixer and on-chip radiator simultaneously. In particular, theory and design methodology of a dual transmission line feedback scheme are presented, which maximizes the transistor gain near its cut-off frequency fmax. The dual-frequency-comb scheme does not only improve the scanning speed by 20 x, but also reduces the overall energy consumption to 90 mJ/point with 1 Hz bandwidth (or 0.5 s integration time). With its channelized 100-GHz scanning range and sub-kHz specificity, wide range of molecules can be detected. In the measurements, state-of-the-art total radiated power of 5.2 mW and single sideband noise figure (NF) of 14.6~19.5 dB are achieved, which further boost the scanning speed and sensitivity. Lastly, spectroscopic measurements for carbonyl sulfide (OCS) and acetonitrile (CH3CN) are presented. With a path length of 70 cm and 1 Hz bandwidth, the measured minimum detectable absorption coefficient reaches [alpha] gas,min=7 .2 x 10-7 cm- 1 . For OCS, that enables a minimum detectable concentration of 11 ppm. The predicted sensitivity for some other molecules reaches ppm level (e.g. 3 ppm for hydrogen cyanide (HCN)), or 10 ppt level if gas pre-concentration with a typical gain of 10 5 is used.","abstract_html":"Millimeter-wave/terahertz rotational spectroscopy of polar gaseous molecules provides a powerful tool for complicated gas mixture analysis. Here, a 220-to-320 GHz dual-frequency-comb spectrometer in 65-nm bulk CMOS is presented, along with a systematic analysis on fundamental issues of rotational spectrometer, including the impacts of various noise mechanisms, gas cell, molecular properties, detection sensitivity, etc. The spectrometer utilizes two counter-propagating frequency-comb signals to seamlessly scan the broadband spectrum. The comb signal, with 10 equally-spaced frequency tones, is generated and detected by a chain of inter-locked transceivers on chip. Each transceiver is based on a multi-functional electromagnetic structure, which serves as frequency doubler, sub-harmonic mixer and on-chip radiator simultaneously. In particular, theory and design methodology of a dual transmission line feedback scheme are presented, which maximizes the transistor gain near its cut-off frequency fmax. The dual-frequency-comb scheme does not only improve the scanning speed by 20 x, but also reduces the overall energy consumption to 90 mJ/point with 1 Hz bandwidth (or 0.5 s integration time). With its channelized 100-GHz scanning range and sub-kHz specificity, wide range of molecules can be detected. In the measurements, state-of-the-art total radiated power of 5.2 mW and single sideband noise figure (NF) of 14.6~19.5 dB are achieved, which further boost the scanning speed and sensitivity. Lastly, spectroscopic measurements for carbonyl sulfide (OCS) and acetonitrile (CH3CN) are presented. With a path length of 70 cm and 1 Hz bandwidth, the measured minimum detectable absorption coefficient reaches [alpha] gas,min=7 .2 x 10-7 cm- 1 . For OCS, that enables a minimum detectable concentration of 11 ppm. The predicted sensitivity for some other molecules reaches ppm level (e.g. 3 ppm for hydrogen cyanide (HCN)), or 10 ppt level if gas pre-concentration with a typical gain of 10 5 is used.","abstract_has_math":false,"creators":["Wang, Cheng"],"institution":"Massachusetts Institute of Technology","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science.","school":null,"contributors":[],"advisors":["Ruonan Han."],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018","date_published":"2018","updated_at":"2026-07-22T22:22:30Z","subjects":["Electrical Engineering and Computer Science."],"languages":["eng"],"rights":["MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission."],"rights_urls":["http://dspace.mit.edu/handle/1721.1/7582"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1721.1/118025","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Ruonan Han."]},{"key":"dc:contributor.department","label":"Department","values":["Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science."]},{"key":"dc:contributor.other","label":"Dc Contributor Other","values":["Massachusetts Institute of Technology. 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They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission."]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://dspace.mit.edu/handle/1721.1/7582"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1721.1/118025"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.","Cataloged from PDF version of thesis.","Includes bibliographical references (pages 71-75)."]},{"key":"dc:description.abstract","label":"Abstract","values":["Millimeter-wave/terahertz rotational spectroscopy of polar gaseous molecules provides a powerful tool for complicated gas mixture analysis. Here, a 220-to-320 GHz dual-frequency-comb spectrometer in 65-nm bulk CMOS is presented, along with a systematic analysis on fundamental issues of rotational spectrometer, including the impacts of various noise mechanisms, gas cell, molecular properties, detection sensitivity, etc. The spectrometer utilizes two counter-propagating frequency-comb signals to seamlessly scan the broadband spectrum. The comb signal, with 10 equally-spaced frequency tones, is generated and detected by a chain of inter-locked transceivers on chip. Each transceiver is based on a multi-functional electromagnetic structure, which serves as frequency doubler, sub-harmonic mixer and on-chip radiator simultaneously. In particular, theory and design methodology of a dual transmission line feedback scheme are presented, which maximizes the transistor gain near its cut-off frequency fmax. The dual-frequency-comb scheme does not only improve the scanning speed by 20 x, but also reduces the overall energy consumption to 90 mJ/point with 1 Hz bandwidth (or 0.5 s integration time). With its channelized 100-GHz scanning range and sub-kHz specificity, wide range of molecules can be detected. In the measurements, state-of-the-art total radiated power of 5.2 mW and single sideband noise figure (NF) of 14.6~19.5 dB are achieved, which further boost the scanning speed and sensitivity. Lastly, spectroscopic measurements for carbonyl sulfide (OCS) and acetonitrile (CH3CN) are presented. With a path length of 70 cm and 1 Hz bandwidth, the measured minimum detectable absorption coefficient reaches [alpha] gas,min=7 .2 x 10-7 cm- 1 . For OCS, that enables a minimum detectable concentration of 11 ppm. The predicted sensitivity for some other molecules reaches ppm level (e.g. 3 ppm for hydrogen cyanide (HCN)), or 10 ppt level if gas pre-concentration with a typical gain of 10 5 is used."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["S.M."]},{"key":"dc:title","label":"Title","values":["Wideband and fast THz spectrometer using dual-frequency-comb on CMOS"]}]}],"canonical_facts":{"dc:contributor.advisor":["Ruonan Han."],"dc:contributor.department":["Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science."],"dc:contributor.other":["Massachusetts Institute of Technology. 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Here, a 220-to-320 GHz dual-frequency-comb spectrometer in 65-nm bulk CMOS is presented, along with a systematic analysis on fundamental issues of rotational spectrometer, including the impacts of various noise mechanisms, gas cell, molecular properties, detection sensitivity, etc. The spectrometer utilizes two counter-propagating frequency-comb signals to seamlessly scan the broadband spectrum. The comb signal, with 10 equally-spaced frequency tones, is generated and detected by a chain of inter-locked transceivers on chip. Each transceiver is based on a multi-functional electromagnetic structure, which serves as frequency doubler, sub-harmonic mixer and on-chip radiator simultaneously. In particular, theory and design methodology of a dual transmission line feedback scheme are presented, which maximizes the transistor gain near its cut-off frequency fmax. The dual-frequency-comb scheme does not only improve the scanning speed by 20 x, but also reduces the overall energy consumption to 90 mJ/point with 1 Hz bandwidth (or 0.5 s integration time). With its channelized 100-GHz scanning range and sub-kHz specificity, wide range of molecules can be detected. In the measurements, state-of-the-art total radiated power of 5.2 mW and single sideband noise figure (NF) of 14.6~19.5 dB are achieved, which further boost the scanning speed and sensitivity. Lastly, spectroscopic measurements for carbonyl sulfide (OCS) and acetonitrile (CH3CN) are presented. With a path length of 70 cm and 1 Hz bandwidth, the measured minimum detectable absorption coefficient reaches [alpha] gas,min=7 .2 x 10-7 cm- 1 . For OCS, that enables a minimum detectable concentration of 11 ppm. The predicted sensitivity for some other molecules reaches ppm level (e.g. 3 ppm for hydrogen cyanide (HCN)), or 10 ppt level if gas pre-concentration with a typical gain of 10 5 is used."],"dc:description.degree":["S.M."],"dc:identifier.uri":["http://hdl.handle.net/1721.1/118025"],"dc:language.iso":["eng"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission."],"dc:rights.uri":["http://dspace.mit.edu/handle/1721.1/7582"],"dc:subject":["Electrical Engineering and Computer Science."],"dc:title":["Wideband and fast THz spectrometer using dual-frequency-comb on CMOS"],"dc:type":["Thesis"]},"updated_at":"2026-07-22T22:22:30Z"}