A topology capable of implementing filters with Gaussian kernel impulse responses is introduced in this work. This is achieved through the utilization of a curve-fitting based approximation method which leads to rational integer-order transfer functions of the same form in the considered cases. The implementation is based on the utilization of Current Feedback Operational Amplifiers as the active elements and the attractive offered benefit is that the core configuration remains un-altered and only the associated interfacing circuit must be changed. The provided simulation results, derived using the OrCAD PSpice design suite confirm the validity of the introduced concept.

Realizations of first–order programmable negative group delay filters for restoring delays in signal processing are presented in this work. This is achieved by designing bilinear filters employing Operational Transconductance Amplifiers for electronic tuning capability, as well as using a Field Programmable Analog Array device for digital programmability. The behavior of the presented filters is evaluated through simulation and experimental results.

Simple designs of controllers which are suitable for biomedical applications of glucose level and dose of irinotecan control are presented in this work. Both integer and non-integer-order proportional-integral controllers are considered with the last ones approximated by an appropriate curve-fitting based method. The resulting rational integer-order impedance function is realized using a Foster type-I RC network. The behavior of the resulting schemes is evaluated through the employment of the OrCAD PSpice software.

Versatile structures capable of implementing Mittag- Leffler kernels in frequency-domain are presented in this work. A curve-fitting approximation method is employed to approximate the transfer functions of the filters, deriving a rational integer-order transfer function. This function is realized using a multi-feedback topology offering electronic tuning capability, due to the employing of Operational Transconductance Amplifiers, as well as using a Field Programmable Analog Array implementation offering digital programmability. The behavior of the presented topologies is evaluated through simulation and experimental results, along with a real–life application example of denoising an electrocardiogram signal.

In this short paper, we propose new voltage- and current- controlled negative impedance converter (NIC) circuits based on two operational amplifiers in a positive and negative feedback configuration. The proposed circuits have a wider linear range than the classical single and dual op amp NICs and better frequency response. Simulations and experimental results are presented to confirm the theoretical analysis.

Fractional-order filters whose impulse response is a Mittag-Leffler (M-L) function in any of its known forms are summarized in this work. Efficient approximation and design of these filters is then achieved through the utilization of a curve-fitting-based method, which simultaneously minimizes the error in filter magnitude and phase. This class of filters is labeled as the "time-domain M-L filters," which is different from the "frequency-domain M-L filters" class recently reported in the literature. In particular, the former class has an impulse response function based on M-L kernel, whereas the latter has a transfer function based on this kernel. Simulation results using Cadence and experimental results using a field programmable analog array (FPAA) validate the introduced concept for selected cases.

In this short paper, we introduce and implement a fractional-order integrator combined with a fractional-delay. This element has an impulse response that smoothly changes between a Dirac delta function (characteristic of an ideal unit delay) and a step-function (characteristic of an ideal integrator) as the fractional-order of integration is varied. We show how to approximate and implement this element using a Field Programmable Analog Array (FPAA) device, and then consider its application in the design of a fractional-order controller with dead time.

This paper presents Cadence and MATLAB Simulink models of the Warburg constant phase element (CPE) used in fractional-order circuits. The Warburg element is a crucial component for modeling the frequency-dependent resistance to mass transport (diffusion) in electrochemistry. The Warburg CPE is modeled using the OTA-C inverse follow-the-leader feedback (IFLF) circuit in Cadence and the follow-the-leader (FLF) circuit in MATLAB. In both models, fourth-order circuits using a continued fraction expansion (CFE) approximation are presented. Block diagrams and signal-flow graph analysis are used to design the circuits. Detailed design procedures and analysis are provided. The IFLF structure, using the OTA-C realization, is analyzed under pre-layout and post-layout conditions and shown to be a feasible element. The FLF structure has been shown to be convenient for use as a MATLAB/Simulink element.

The lung bio-heat transfer electrical equivalent which is described by a fractional-order impedance is approximated through the utilization of a curve-fitting based method. The resulting rational integer-order impedance function is realized using a Foster type-I RC network. The derived MATLAB and OrCAD PSpice simulation results confirm the validity of the introduced approximation concept as well as the correct operation of the presented circuitry.

In this paper, a new lossless floating capacitance multiplier (FCM) using a single inverting type differential difference current conveyor (DDCC-) is proposed. Only 16 MOS transistors are used in the internal structure of the DDCC-. The proposed FCM includes a canonical number of passive components. Passive element matching requirements are unnecessary for the proposed FCM. The proposed FCM exhibits low power dissipation, and for a multiplication factor of 500, its operating frequency range extends from approximately 22 mHz to 500 kHz. Simulation results indicate that the operating frequency range remains unaffected with the temperature variations. The proposed FCM is tested in the application example and experimentally with AD844s. All simulations by using the SPICE program are accomplished.

This work presents a complete deep-learning-driven automation flow for designing ultra-low-power subthreshold operational transconductance amplifiers used in electronically tunable gm-C resonator and anti-resonator circuits for speech vowel processing. A multi-task learning neural network is trained as an accurate and extremely fast metamodel (surrogate) of an 8-parameter operational transconductance amplifier topology in 350 nm CMOS process node. Using only 60000 Latin-hypercube-sampled circuit simulations for training, the metamodel predicts DC power consumption, total transistor area, and DC transconductance with average errors of 2.9%, 5.0%, and 7.3%, respectively. The trained model is then coupled with the NSGA-II multi-objective genetic algorithm to instantly generate Pareto-optimal trade-offs between power and area for any designer-specified gm value in the 45-55 nA/V range typical of vowel formant filters. Compared to conventional simulation-in-the-loop NSGA-II optimization, the proposed flow reduces the total design time from 25 h to 7 h, a 3.5 times speedup, and against the standard human design methodology, the acceleration is higher than 20 times. The methodology enables on-the-fly power/area optimization of all operational transconductance amplifiers in sixth-order tunable vowel filters without need for re-design.

A brief report on the event “IEEE CASS @ 8th Panhellenic Conference on Electronics and Telecommunications (PACET 2026)” held at University of Patras, Greece is presented. This report covers the scope of the event accompanied by relevant photos.

In this work, we show how higher-order low-pass, high-pass, band-pass or band-stop filter functions can be systematically obtained using the Mittag-Leffler (ML) function as a basic building block. In particular, by multiplying (i.e. cascading) two or more ML functions; each having the form of a two-parameter ML function E-alpha,E-beta(z),(0) (0 <= alpha,beta <= 1) with its argument z being equal to-s or-1/s (s is the complex frequency; i.e. s = j omega), higher-order fractional filters can be obtained. We focus here on the cascade of two ML functions, which produces second-order transfer functions (as a special case) when alpha= 0 and beta= 1. We derive in closed form the impulse response and step-response of these filters and experimentally verify their behavior after approximating the ML function using a suitable integer-order approximation. It is worth mentioning that this class of filters does not employ the fractional-order Laplace operator s(+/- r)(0 < gamma <= 1), unlike classical fractional-order filters.

This paper presents a unified and flexible framework for implementing auditory-inspired filters based on the Gamma Kernel. The proposed structure enables both Gammatone and Gammachirp filters to be realized using the same configuration, providing a compact and versatile design suitable for auditory modeling and signal processing applications. This is achieved through the utilization of a curve-fitting technique in MATLAB that approximates the Laplace transform of each filter’s impulse response, leading to a rational integer-order transfer function. By adjusting the coefficient values of this function both Gammatone and Gammachirp filter-banks can be implemented, significantly simplifying the design and tuning process. An auditory filter example implemented on a Field Programmable Analog Array (FPAA) device is demonstrated, where magnitude and impulse responses are both evaluated.

A Semi–Gaussian CR − (RC)3 pulse shaper, applicable in nuclear electronic systems is presented in this work. This is achieved by cascading a high-pass CR filter with a 3rd-order low-pass RC filter. This work is also focused on a further research about the implementation of the low-pass filter, comparing different approximation methods. The low-pass filter is realized using the Maclaurin series approximation and is implemented, as the high-pass filter, employing Operational Transconductance Amplifiers. The low-pass filter is also realized using a Field Programmable Analog Array device. The behavior of the presented topologies is evaluated through simulation and experimental results.

The behavior of the cascade connection of two filters each having a true Gaussian impulse response function is studied in this work. It is particularly shown that the impulse response of the resulting higher-order filter is not a true Gaussian function, as might initially be assumed based on the properties of the Gaussian distribution. To validate our findings, an approximation of the cascade filter transfer function was performed through the employment of a curve-fitting technique, and simulations as well as experimental results (using a Field Programmable Analog Array) are shown to match well with the theory.

This work presents novel designs of multifunction topologies for simultaneously extracting the real and imaginary components of complex band-pass and notch filters, which are derived from prototype first-order low-pass and high-pass filters. The real and imaginary parts of the complex filters are then post-processed to compute the instantaneous magnitude. The performance of both the multifunction topologies and post-processing stages is evaluated using the OrCAD PSpice suite, as well as through experimental results.

Integer and non-integer-order exponential filters defined in both the time and frequency-domains are investigated in this work. These filters are then approximated utilizing a curve-fitting method leading to a rational integer-order approximating transfer function. The accuracy of the approximation of the exponential filters is confirmed through experimental results obtained using a Field Programmable Analog Array device. A real life application example is also provided, where one of the presented filters is employed for denoising an electrocardiogram signal.

A novel approach for implementing first-order complex filters without the requirement of two separate signal paths, for the real and imaginary parts of the transfer function, is introduced in this work. This is achieved by employing a curve-fitting based method to approximate both the gain and phase responses of the prototype complex filter. The resulting rational integer-order transfer function can be realized using conventional filter design techniques. The behavior of the proposed complex resonator configuration is evaluated through experimental results, derived using a Field Programmable Analog Array (FPAA) device. An application example is provided, in which the complex resonator is employed to extract vowels from the corresponding glottal pulse trains.