{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,15]],"date-time":"2025-11-15T10:32:25Z","timestamp":1763202745415,"version":"build-2065373602"},"reference-count":17,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2023,7,31]],"date-time":"2023-07-31T00:00:00Z","timestamp":1690761600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005073","name":"Nano UAV Intelligence Systems Research Laboratory program of Defense Acquisition Program Administration and Agency for Defense Development","doi-asserted-by":"publisher","award":["UD200027ED"],"award-info":[{"award-number":["UD200027ED"]}],"id":[{"id":"10.13039\/501100005073","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper presents a wideband 4-bit true time delay IC using a 0.25 \u03bcm GaN HEMT (High-Electron-Mobility Transistor) process for the beam-squint-free phased array antennas. The true time delay IC is implemented with a switched path circuit topology using DPDT (Double Pole Double Throw) with no shunt transistor in the inter-stages to improve the bandwidth and SPDT (Single Pole Single Throw) switches at the input and the output ports. The delay lines are implemented with CLC \u03c0-networks with the lumped element to ensure a compact chip size. A negative voltage generator and an SPI controller are implemented in the PCB (Printed Circuit Board) due to the lack of digital control logic in GaN technology. A maximum time delay of ~182 ps with a time delay resolution of 10.5 ps is achieved at DC\u20136 GHz. The RMS (Root Mean Square) time delay and amplitude error are &lt;5 ps and &lt;0.6 dB, respectively. The measured insertion loss is &lt;6.8 dB and the input and output return losses are &gt;10 dB at DC\u20136 GHz. The current consumption is nearly zero with a 3.3 V supply. The chip size including pads is 2.45 \u00d7 1.75 mm2. To the authors\u2019 knowledge, this is the first demonstration of a true time delay IC using GaN HEMT technology.<\/jats:p>","DOI":"10.3390\/s23156827","type":"journal-article","created":{"date-parts":[[2023,7,31]],"date-time":"2023-07-31T10:08:14Z","timestamp":1690798094000},"page":"6827","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["A Wideband True Time Delay Circuit Using 0.25 \u00b5m GaN HEMT Technology"],"prefix":"10.3390","volume":"23","author":[{"given":"Jeong-Geun","family":"Kim","sequence":"first","affiliation":[{"name":"Department of Electronic Engineering, Kwangwoon University, Seoul 01897, Republic of Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0675-1115","authenticated-orcid":false,"given":"Donghyun","family":"Baek","sequence":"additional","affiliation":[{"name":"School of Electrical Engineering, Chung-Ang University, Seoul 06974, Republic of Korea"}]}],"member":"1968","published-online":{"date-parts":[[2023,7,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1109\/LMWC.2021.3115411","article-title":"Continuous Broadband GaAs and GaN MMIC Phase Shifters","volume":"32","author":"Robinson","year":"2022","journal-title":"IEEE Microw. Wirel. Compon. Lett."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Kang, D., and Hong, S. (2007, January 3\u20135). A 2\u201310 GHz Digital CMOS Phase Shifter for Ultra-Wideband Phased Array System. Proceedings of the 2007 IEEE Radio Frequency Integrated Circuits Symposium, Honolulu, HI, USA.","DOI":"10.1109\/RFIC.2007.380909"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"693","DOI":"10.4218\/etrij.2018-0113","article-title":"CMOS true-time delay IC for wideband phased-array antenna","volume":"40","author":"Kim","year":"2018","journal-title":"ETRI J."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Cho, M., Han, J., Kim, J., and Kim, J. (2014, January 1\u20136). An X\/Ku-band Bi-directional true time delay T\/R chipset in 0.13 \u03bcm CMOS technology. . Proceedings of the IEEE MTT-S International Microwave Symposium, Tampa, FL, USA.","DOI":"10.1109\/MWSYM.2014.6848608"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"193","DOI":"10.5573\/JSTS.2013.13.3.193","article-title":"A 5\u201320 GHz 5-Bit True Time Delay Circuit in 0.18 \u00b5m CMOS Technology","volume":"13","author":"Choi","year":"2013","journal-title":"J. Semicond. Technol. Sci."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Willms, J., Ouacha, A., Boer, L., and Vliet, F. (2000, January 2\u20135). A wideband GaAs 6-bit true-time delay MMIC employing on-chip digital drivers. Proceedings of the 2000 European Microwave Conference, Paris, France.","DOI":"10.1109\/EUMA.2000.338753"},{"key":"ref_7","unstructured":"Ouacha, A., Alfredson, M., and Wilden, H. (2004, January 11\u201315). 638 mm Relative Delay 9-Bits MMIC TTD for Active Phased Array SAR\/MTI. Proceedings of the 2004 European Microwave Conference, Amsterdam, The Netherlands."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3053","DOI":"10.1109\/TMTT.2019.2901678","article-title":"Continuous True-Time Delay Phase Shifter Using Distributed Inductive and Capacitive Miller Effect","volume":"67","author":"Lee","year":"2019","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1881","DOI":"10.1109\/22.734503","article-title":"Distributed MEMS True-Time Delay Phase Shifters and Wide-Band Switches","volume":"46","author":"Barker","year":"1998","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1109\/7260.914301","article-title":"A DC-to-40 GHz Four-Bit RF MEMS True-Time Delay Network","volume":"11","author":"Kim","year":"2001","journal-title":"IEEE Microw. Wirel. Compon. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"2727","DOI":"10.1109\/TAP.2020.3030993","article-title":"True-Time-Delay Mechanical Phase Shifter in Gap Waveguide Technology for Slotted Waveguide Arrays in K a-Band","volume":"69","year":"2021","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1119","DOI":"10.1109\/LMWC.2017.2763754","article-title":"4\u201320 GHz GaAs True-Time Delay Amplifier MMIC","volume":"27","author":"Shin","year":"2017","journal-title":"IEEE Microw. Wirel. Compon. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"622","DOI":"10.1587\/transele.2018ECS6022","article-title":"7-Bit Multilayer True-Time Delay up to 1016 ps for Wideband Phased Array Antenna","volume":"E102-C","author":"Yoon","year":"2019","journal-title":"IEICE Trans. Electron."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2834","DOI":"10.1109\/JSSC.2007.908746","article-title":"An Integrated Ultra-Wideband Timed Array Receiver in 0.13 \u03bcm CMOS Using a Path-Sharing True Time Delay Architecture","volume":"42","author":"Chu","year":"2007","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1542","DOI":"10.1109\/TMTT.2019.2959319","article-title":"Novel Trombone Topology for Wideband True-Time-Delay Implementation","volume":"68","author":"Ghazizadeh","year":"2020","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"889","DOI":"10.1109\/LMWC.2021.3075990","article-title":"A Low Insertion Loss Variation Trombone True Time Delay in GaAs pHEMT Monolithic Microwave Integrated Circuit","volume":"31","author":"Hao","year":"2021","journal-title":"IEEE Microw. Wirel. Compon. 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