## 1 Introduction
It is implemented by connecting a FO capacitor to a circuit that provides immittance inversion, as is the case of the gyrator, immittance inverter, or generalized immittance converter (GIC) [19]. This approach using a gyrator with two operational transconductance amplifiers (OTAs) is also discussed in this article. As it is not possible to manufacture perfectly ideal active elements, it is appropriate to analyze the influence of parasitic properties of these elements on the function of the gyrator. Thus, limitations on the performance of a gyrator transforming FO capacitor to FO inductor, due to non-ideal OTA properties are presented here in detail. Deviations in magnitude and phase admittance characteristics are investigated, and guidelines for minimizing these errors are provided. Moreover, design steps for optimal utilization of OTA signal dynamic range are given. A similar approach of obtaining FO inductor by means of immittance inversion has also been presented in several recent works [20; 21; 22]. In Reference [20], an opamp-based GIC is employed to obtain grounded FOEs with impedance phasor in any of the four quadrants, therefore, FO inductor is also included. The guidelines for obtaining passive element parameters for the required fractance value are given; however, there is no thorough analysis of the effect of opamp non-idealities. The paper [21] is devoted to the optimal design of a grounded FO inductor using GIC, and a detailed study of the influence of opamp non-idealities is given there. This work aims to provide similar analysis and design guidelines; however, here we deal with a gyrator, which is a more suitable solution compared to GIC regarding the number of elements. It is based on only one loading passive element and two OTAs; whereas, the FO inductor in Reference [21] contains five passive elements and two opamps. In contrast to Reference [21], the circuit in this work provides a FO inductor with electronically adjustable fractance, and it can be easily converted to a floating variant by using one of the OTAs with differential outputs. Among the works dealing with FO inductors, which contain an analysis of active element parasitic properties,the paper [22] can also be mentioned. However, here a lossy FO inductor is implemented by a current feedback operational amplifier (CFOA) and FO capacitor. The analysis of parasitic properties is performed only at the level of symbolic relations, and the influence of individual CFOA parasitis on the properties of the FO inductor is not explained. This paper is organized as follows: In Section 2, the theory of OTA-based gyrator implementing FO inductance simulator is described. The influence of OTA parasitic properties on the gyrator function is analyzed, and dynamic properties are studied to prevent the amplifiers from overloading. Design guidelines and compensation possibilities are given to minimize the effect of the parasitic properties. Section 3 contains verification of the theoretical findings by PSpice simulations. The practical design of FO inductor for an electrical model of the human respiratory system is demonstrated as an example. Finally, our conclusions are given in Section 4.