Detail publikace

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

ŠOTNER, R. BLACK, C. JEŘÁBEK, J. FREEBORN, T. COLBURN, S. SVOBODA, M.

Originální název

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

Typ

článek v časopise ve Web of Science, Jimp

Jazyk

angličtina

Originální abstrakt

This 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.

Klíčová slova

Adjustability; Constant phase element; Fractional-order; MOSFET; Pseudocapacitance; Tunability; Varicap

Autoři

ŠOTNER, R.; BLACK, C.; JEŘÁBEK, J.; FREEBORN, T.; COLBURN, S.; SVOBODA, M.

Vydáno

1. 7. 2025

Nakladatel

Springer Nature

ISSN

2045-2322

Periodikum

Scientific Reports

Ročník

15

Číslo

7

Stát

Spojené království Velké Británie a Severního Irska

Strany od

1

Strany do

17

Strany počet

17

URL

https://www.nature.com/articles/s41598-025-07319-5

Plný text v Digitální knihovně

http://hdl.handle.net/11012/255157

BibTex

@article{BUT198331,
  author="Roman {Šotner} and Chloe {Black} and Jan {Jeřábek} and Todd {Freeborn} and Simon {Colburn} and Marek {Svoboda}",
  title="Practical design of variable fractional-order capacitors with a single tuning feature using field effect transistors and variable capacitance diodes",
  journal="Scientific Reports",
  year="2025",
  volume="15",
  number="7",
  pages="17",
  doi="10.1038/s41598-025-07319-5",
  issn="2045-2322",
  url="https://www.nature.com/articles/s41598-025-07319-5"
}