Comparative Study of Op-Amp-based Integrators Suitable for Fractional-Order Controller Design

Herencsar N., Kartci A., Yildiz H. A., Sotner R., Dvorak J., Kubanek D., ...More

42nd International Conference on Telecommunications and Signal Processing (TSP), Budapest, Hungary, 1 - 03 July 2019, pp.740-743 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Doi Number: 10.1109/tsp.2019.8768843
  • City: Budapest
  • Country: Hungary
  • Page Numbers: pp.740-743
  • Istanbul Technical University Affiliated: Yes


In this paper, a fractional-order capacitor (FOC) of an order lambda = 0.89 (i.e. constant phase angle -80.1 degree) was emulated via Valsa RC network with five branches. The network component values were optimized using modified least squares quadratic method in a wide frequency range of 100 mHz-1 kHz (i.e. 4 decades) and maximum relative phase error 0.78% was obtained. The design specification corresponds to a speed control system of an armature controlled DC motor, which is often used in control theory. Overall performance evaluation shows the product of evaluated key features (e.g. phase angle deviation and absolute values of relative phase, impedance, and pseudocapacitance errors) for the optimized FOC is 13.3% less than the one obtained via Valsa approximation. The behavior of Op-Amp-based non-inverting configurations of analogue fractional-order integral operator s(-lambda) employing the optimized FOC, where 0