Electronically Tunable Fully-Differential Fractional-Order Low-Pass Filter

The paper presents proposal of a fully- differential (1 + )-order low-pass filter. The order of the filter and its cut-off frequency can be controlled electronically. The filter is proposed using operational transconductance amplifiers (OTAs), adjustable current amplifiers (ACAs) and fully-differential current follower (FD-CF). The circuit structure is based on well-known Inverse Follow-the-Leader Feedback (IFLF) topology. Design correctness of the proposed filter is supported by PSpice simulations with transistor-level simulation models. The ability of the electronic control of the order has been tested for five individual values of parameter . Furthermore, the ability of the electronic control of the cut-off frequency of the filter has been also tested for five different values. Additionally, the simulation results of the proposed fully-differential (F-D) filter are compared with the results of the single-ended (S-E) equivalent of the presented filter

Tunable Fractional-Order Capacitance Multiplier Using Current Gain Adjustment

This paper brings new solution of linearly adjustable fractional-order capacitance multiplier. The adjustable current gain, linear in wide range of input current and with linear dependence on driving voltage, serves for these purposes and offers one-decade variation of equivalent capacity (pseudo-capacitance) between 24 and 429 F/sec^0.75 . The operational range was tested by PSpice simulations and by measurement using RC approximant of constant phase element of the order 0.25 in bandwidth from 20 Hz up to 1 MHz

A Fractional-Order Transitional Butterworth-Butterworth Filter and Its Experimental Validation

This paper introduces the generalization of the classical Transitional Butterworth-Butterworth Filter (TBBF) to the Fractional-Order (FO) domain. Stable rational approximants of the FO-TBBF are optimally realized. Several design examples demonstrate the robustness and modeling efficacy of the proposed method. Practical circuit implementation using the current feedback operational amplifier employed as an active element is presented. Experimental results endorse good agreement (R2= 0.999968) with the theoretical magnitude-frequency characteristic

Analog electronic circuit design of the Cao 4D hyperchaotic finance system

Chaotic and hyperchaotic systems have been used in different fields of science in recent years. Many chaotic and hyperchaotic systems with different behaviors have been introduced in the literature. Especially in chaotic system based encryption, random number generator and communication applications, hyperchaotic systems are more preferred because of their more complex characteristics. The chaotic and hyperchaotic systems introduced in the literature are generally presented only as numerical simulation. However, it is necessary to design the electronic circuit for the use of the systems in real applications. In this study, numerical simulation results of four-dimensional (4D) hyperchaotic finance system introduced by Cao in 2018 were obtained and then analog electronic circuit design was realized. Numerical simulation results and designed electronic circuit outputs have confirmed each other. As a result, it is ensured that Cao 4D hyperchaotic finance system can be used in real engineering applications

Low Power IoT based Automated Manhole Cover Monitoring System as a Smart City application

With the increased population in the big cities, Internet of Things (IoT) devices to be used as automated monitoring systems are required in many of the Smart city’s applications. Monitoring road infrastructure such as a manhole cover (MC) is one of these applications. Automating monitoring manhole cover structure has become more demanding, especially when the number of MC failure increases rapidly: it affects the safety, security and the economy of the society. Only 30% of the current MC monitoring systems are automated with short lifetime in comparison to the lifetime of the MC, without monitoring all the MC issues and without discussing the challenges of the design from IoT device design point of view. Extending the lifetime of a fully automated IoT-based MC monitoring system from circuit design point of view was studied and addressed in this research. The main circuit that consumes more power in the IoT-based MC monitoring system is the analogue to digital converter (ADC) found at the data acquisition module (DAQ). In several applications, the compressive sensing (CS) technique proved its capability to reduce the power consumption for ADC. In this research, CS has been investigated and studied deeply to reach the aim of the research. CS based ADC is named analogue to information converter (AIC). Because the heart of the AIC is the pseudorandom number generator (PRNG), several researchers have used it as a key to secure the data, which makes AIC more suitable for IoT device design. Most of these PRNG designs for AIC are hardware implemented in the digital circuit design. The presence of digital PRNG at the AIC analogue front end requires: a) isolating digital and analogue parts, and b) using two different power supplies and grounds for analogue and digital parts. On the other hand, analogue circuit design becomes more demanding for the sake of the power consumption, especially after merging the analogue circuit design with other fields such as neural networks and neuroscience. This has motivated the researcher to propose two low-power analogue chaotic oscillators to replace digital PRNG using opamp Schmitt Trigger. The proposed systems are based on a coupling oscillator concept. The design of the proposed systems is based on: First, two new modifications for the well-known astable multivibrator using opamp Schmitt trigger. Second, the waveshaping design technique is presented to design analogue chaotic oscillators instead of starting with complex differential equations as it is the case for most of the chaotic oscillator designs. This technique helps to find easy steps and understanding of building analogue chaotic oscillators for electronic circuit designers. The proposed systems used off the shelf components as a proof of concept. The proposed systems were validated based on: a) the range of the temperature found beneath a manhole cover, and b) the signal reconstruction under the presence and the absence of noise. The results show decent performance of the proposed system from the power consumption point of view, as it can exceed the lifetime of similar two opamps based Jerk chaotic oscillators by almost one year for long lifetime applications such as monitoring MC using Li-Ion battery. Furthermore, in comparison to PRNG output sequence generated by a software algorithm used in AIC framework in the presence of the noise, the first proposed system output sequence improved the signal reconstruction by 6.94%, while the second system improved the signal reconstruction by 17.83

Reconnection–less Reconfigurable Fractional–Order Current–Mode Integrator Design with Simple Control

A design of a fractional-order (FO) integrator is introduced for operation of resulting solution in the current mode (CM). The solution of the integrator is based on the utilization of RC structures, but in comparison to other RC structure based FO designs, the proposed integrator offers the electronic control of the order. Moreover, the control of the proposed integrator does not require multiple specific and accurate values of the control voltages/currents in comparison to the topologies based on the approximation of the FO Laplacian operator. The electronic control of a gain level (gain adjustment) of the proposed integrator is available. The paper offers the results of Cadence IC6 (spectre) simulations and more importantly experimental measurements to support the presented design. The proposed integrator can be used to build various FO circuits as demonstrated by the utilization of the integrator into a structure of a frequency filter in order to provide FO characteristics

Imperfections in Integrated Devices Allow the Emergence of Unexpected Strange Attractors in Electronic Circuits

The realization of integrated devices determines unavoidable imperfections which are linked to the manufacturing process, thus making them imperfect systems. Imperfection is not always detrimental, as it can lead to unexpected complex and organized behaviors. In this paper we explore the possibility of designing imperfect electronic circuits producing a chaotic flow with bandwidth up to the order to several megahertz thanks to the hidden dynamics induced by construction imperfections, and whose characteristics can be tuned by means of a single variable resistor, acting as bifurcation parameter. Moreover, a strategy to estimate the parameters of the hidden dynamics is devised and the synchronization of imperfect chaotic circuits is shown. The paper further remarks that imperfection can play an important role in the realization of robust chaos generators based on simple circuits