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A structure suitable for implementing power-law low-pass and high-pass filter transfer functions is presented in this work. Through the utilization of a field-programmable analog array device, full programmability of the characteristics of the intermediate stages, as is required for realizing the rational integer-order transfer function that approximates the corresponding power-law function, was achieved, making the structure versatile. In addition, a comparison between power-law and fractional-order filters regarding the effect of the non-integer order was performed. The presented design examples are fully supported by experimental results.

Topologies of power-law proportional-integral controllers, which offer minimization of the active component count are presented in this work. This is achieved thanks to the utilization of RC networks, which approximate driving-point impedances described by power-law functions. Additional important features of the presented schemes are their capability of achieving minimization of the spread of passive elements, as well as of implementing values of order greater than one.

In this paper, the application of the theory of Lissajous figures to the creation of pinched hysteresis loops, considered to be a characteristic of memristive systems, is demonstrated and experimentally verified using designed electronic circuits in the form of an input impedance. The relationship between the Lissajous-based model of the pinched hysteresis loop and a previously reported integrator-multiplier model is clarified. Important special cases are highlighted and necessary conditions to obtain a pinch point, loops with positive or negative inclination, as well as no pinch point are given. We show that in devices (memristors or other devices) and circuits which exhibit this behavior, a nonlinearity that performs the necessary frequency doubling mandated by the theory must exist.

This brief presents a novel compact CMOS Fully Differential Difference Amplifier (FDDA) structure suitable for extremely low-voltage low-power applications. Unlike the conventional FB-DDAs that employ two differential pairs, the proposed structure employs one differential pair of multiple-input bulk-driven MOS transistor (MI-BD MOST) that results in reduced count of current branches and, consequently, of power consumption. The proposed FDDA has the simplest CMOS structure presented in the literature so far. Furthermore, while the voltage supply is 0.5 V and the power consumption is 246.6 nW the circuit enjoys rail-to-rail input common mode range (ICMR), high common mode rejection ratio (CMRR) of 100.3 dB @ DC, power supply rejection ratio (PSRR) of 127.8 dB@ DC, voltage gain of 61.4 dB and gain bandwidth product of 6.98 kHz for 30 pF capacitive load. The total harmonic distortion (THD) is less than 0.08% for 500 mV/1 kHz input sine wave signal. The circuit was designed and simulated in Cadence/Spectre environment using 0.18 µm CMOS process from TSMC.

A low-pass fractional-order filter topology based on a single metal oxide semiconductor transistor is presented in this Letter. The filter is realized using a fractional-order capacitor fabricated using multi-walled carbon nanotubes. The electronic tuning capability of the filter’s frequency characteristics is achieved through a biasing current source. Experimental results are presented and compared with the theory.

A novel topology for simultaneous emulation of fractional-order capacitors and inductors is presented in this paper. In particular, only one control terminal is used in order to select the type of the element as well as its fractional order. This is achieved through an appropriate fitting of the expressions of the intermediate bias currents, in such a way that, eventually, only the adjustment of one main bias current is required. The performance of the proposed topology is evaluated through post-layout simulations using Cadence and Austria Mikro Systeme (AMS) 0.35 μ m CMOS process.

A magnetic levitation plant is a fast, unstable, nonlinear mechatronic system vulnerable to measurement noise and external interference. Designing a high-performance and robust controller for such system, immune to noise and disturbances, and ensuring a wide operating region, is a challenging task. One can chose a well-know LQI controller, designed based on a linearized plant model, to stabilise the system and to eliminate the steady-state error. However, large plant-model mismatch and considerable non-linearity of the system may limit the control quality provided by such a solution. To improve the system performance one can introduce some additional degrees of freedom by replacing the integer order integrator with a fractional one. For practical implementation, the latter may be approximated with an integer-order realisation obtained with the time-domain Oustaloup method. The paper explains the idea of an $\text{LQI}^{\beta}$ controller, presents selected results of simulation tests of the closed-loop control system behaviour, and provides discussion of possible applications and advantages of the proposed approach.

An electronically adjustable realization of the three-element Windkessel model, thanks to the employment of an Operational Transconductance Amplifier-based structure, is presented in this work. Instead of following the typical method where the fractional-order capacitor is substituted by its active emulator, in this case the whole impedance is considered for the implementation of the model. The approximation of the total impedance function is performed through the utilization of an appropriate curve-fitting-based technique, which, compared to the conventional method where the approximation of the Laplacian operator is performed, offers improved accuracy. The presented post-layout simulation results, obtained using the Cadence IC design suite and MOS transistors models provided by the Austria Mikro Systeme (AMS) CMOS process, confirm the correct operation of the developed topology.

A novel procedure for compact realization of complex, multiple-parameter impedance functions is introduced in this paper. The concept is based on the consideration of the whole impedance function and the approximation of its frequency characteristics through a suitable curve-fitting-based algorithm, instead of separately approximating the intermediate terms of the function. In this way, the total impedance is implemented by a topology which is based on one transfer function, offering the benefit of reduced complexity. The impedance function that describes the electrical properties of edible drinks can be considered as a characteristic example and, therefore, is used for the verification of the proposed concept. Different samples of drinks, red wine from Bairrada, semi-skimmed and organic semi- skimmed milk, are considered with the behavior of the proposed schemes being evaluated through simulation and experimental results.