Practical design of variable fractional-order capacitors with a single tuning feature using field effect transistors and variable capacitance diodes

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dc.contributor.authorŠotner, Romancs
dc.contributor.authorBlack, Chloecs
dc.contributor.authorJeřábek, Jancs
dc.contributor.authorFreeborn, Toddcs
dc.contributor.authorColburn, Simoncs
dc.contributor.authorSvoboda, Marekcs
dc.coverage.issue7cs
dc.coverage.volume15cs
dc.date.accessioned2025-07-15T10:56:21Z
dc.date.available2025-07-15T10:56:21Z
dc.date.issued2025-07-01cs
dc.description.abstractThis paper presents two discrete circuit solutions for realizing passive, electronically adjustable constant-phase elements, specifically half-order capacitors with a -45 degrees phase shift. Fractional-order capacitors with electronically adjustable pseudocapacitance are especially useful for designing tunable filters and oscillators. The ability to adjust pseudocapacitance electronically and continuously is a major improvement over traditional passive solutions. Their pseudocapacitance can be controlled by a DC voltage, allowing key parameters like the cut-off or oscillation frequency to be tuned. Two presented design approaches differ in accuracy, tuning range, and signal-handling capability. Both solutions maintain a constant phase over one frequency decade, with a phase ripple within +/- 2 degrees. The tuning range spans from hundreds of Hz to several MHz. Presented solutions allow pseudocapacitance tuning in range of hundreds of nano F/sec0.5 (with varicaps) and tens of micro F/sec0.5 (with MOSFETs). The MOS-based circuit offers a tuning ratio of 7 but shows a 19% deviation between simulation and measurement. It also suffers from notable nonlinearity, with undistorted operation limited to signal levels up to 20 mV peak-to-peak. The varicap-based solution achieves a tuning ratio of 5, with high accuracy (up to 6% error), and handles input signals in the hundreds of mV with acceptable distortion. PSpice simulations and laboratory measurements confirm the performance of both designs.en
dc.formattextcs
dc.format.extent1-17cs
dc.format.mimetypeapplication/pdfcs
dc.identifier.citationScientific Reports. 2025, vol. 15, issue 7, p. 1-17.en
dc.identifier.doi10.1038/s41598-025-07319-5cs
dc.identifier.issn2045-2322cs
dc.identifier.orcid0000-0002-2430-1815cs
dc.identifier.orcid0000-0001-9487-5024cs
dc.identifier.orcid0009-0005-4570-8592cs
dc.identifier.other198331cs
dc.identifier.researcheridG-4209-2017cs
dc.identifier.researcheridE-3929-2018cs
dc.identifier.scopus21834721500cs
dc.identifier.scopus23011945600cs
dc.identifier.urihttps://hdl.handle.net/11012/255157
dc.language.isoencs
dc.publisherSpringer Naturecs
dc.relation.ispartofScientific Reportscs
dc.relation.urihttps://www.nature.com/articles/s41598-025-07319-5cs
dc.rightsCreative Commons Attribution 4.0 Internationalcs
dc.rights.accessopenAccesscs
dc.rights.sherpahttp://www.sherpa.ac.uk/romeo/issn/2045-2322/cs
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/cs
dc.subjectAdjustabilityen
dc.subjectConstant phase elementen
dc.subjectFractional-orderen
dc.subjectMOSFETen
dc.subjectPseudocapacitanceen
dc.subjectTunabilityen
dc.subjectVaricapen
dc.titlePractical design of variable fractional-order capacitors with a single tuning feature using field effect transistors and variable capacitance diodesen
dc.type.driverarticleen
dc.type.statusPeer-revieweden
dc.type.versionpublishedVersionen
eprints.grantNumberinfo:eu-repo/grantAgreement/GA0/GA/GA23-06070Scs
sync.item.dbidVAV-198331en
sync.item.dbtypeVAVen
sync.item.insts2025.07.15 12:56:20en
sync.item.modts2025.07.15 12:33:40en
thesis.grantorVysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií. Ústav radioelektronikycs
thesis.grantorVysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií. Ústav telekomunikacícs
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