Fractional-order high-pass filter with electronically adjustable parameters

This paper presents possible solution of fractional-order high-pass filter (FHPF) with electronically adjustable order between 1 and 2 and also with electronically adjustable pole frequency. It is based on well-known Follow-the-Leader Feedback (FLF) topology adjusted for utilization with operational transconductance amplifiers (OTAs) and adjustable current amplifiers (ACAs). This 3rd-order topology is used in order to approximate FHPF response in particular frequency band of interest. Design is supported by Pspice simulations for three particular values of the filter's order (1.25, 1.5, 1.75) and for several values of pole frequency. Moreover, simulation results with two different approximations are compared.