Practically Realizable Circuits for OTRA and their Implementation in Oscillators

In this paper, practical circuits for operational transresistance amplifier (OTRA) realizable in lab using commercial ICs have been designed and proposed. 3 structures based on operational amplifier (OPAMP-LM741), operational transconductance amplifier (OTA-CA3080) and current conveyors II (AD844) have been proposed. In these proposed designs, conditions to mimic the current-voltage behavior of OTRA have been formulated using active and passive components. Moreover, these components are also used to achieve flexibility in transresistance gain of implemented OTRA. The behavior of the proposed OTRA structures have been validated using LTSPICE. Furthermore, to represent practical usability of these designs oscillator circuit have been designed and implemented on software and experimentally also on bread board. All the results prove the OTRA operation of the designed circuits and their usability in the practical environment.

A DVCC-Based Current-Mode First-Order Universal Filter

A current-mode first-order filter configuration simultaneously providing noninverting and inverting low-pass (LP) and high-pass (HP) responses depending on passive element choice is proposed. In addition, all-pass filter (APF) responses can be easily obtained with interconnection of LP and HP output currents. The proposed filter employs only two differential voltage current conveyors, a grounded resistor and a grounded capacitor, so it is suitable for integrated circuit realization. It provides the feature of high output impedance. It does not need any passive element matching constraints. A voltage-mode oscillator based on the inverting APF is presented as a typical application. The performance of the proposed configuration is verified through many SPICE simulation and experimental test results.

DVCC based (2+α) order low pass Bessel filter using optimization techniques

This paper proposes the design and analysis of (2+α) order low pass Bessel filter using different optimization techniques. The coefficients of the proposed filter are found out by minimizing the error between transfer functions of (2+α) order low pass filter and third-order Bessel approximation using simulated annealing (SA), interior search algorithm (ISA), and nonlinear least square (NLS) optimization techniques. The best optimization technique based on the error in gain, cut off frequency, roll-off, passband, stopband, and phase is chosen for designing the proposed filter. The stability analysis of the proposed filter has also been done in W-plane. The simulated responses of the best optimized proposed filter are obtained using the FOMCON toolbox of MATLAB and SPICE. The circuit realization of 2.5 order low pass Bessel filter is done using two DVCCs (differential voltage current conveyors), one generalized impedance converter (GIC) based inductor, and one fractional capacitor. The proposed filter is implemented for the cut off frequency of 10 kHz using a wideband fractional capacitor. Monte Carlo noise analyses are also performed for the proposed filter. The MATLAB and SPICE results are shown in good agreement.

An internally-controlled memristor-based amplitude shift keying modulator

Purpose The purpose of this paper is to design and construct an amplitude shift keying (ASK) modulator, which, using the digital binary modulating signal, controls a floating memristor emulator (MR) internally without the need for additional control circuits to achieve the ASK modulated wave. Design/methodology/approach A binary digital unipolar signal to be modulated is converted by a pre-processor circuit into a suitable bipolar modulating direct current (DC) signal for the control of the MR state, using current conveyors the carrier signal’s amplitude is varied with the change in the memristance of the floating MR. A high pass filter is then used to remove the DC control signal (modulating signal) leaving only the modulated carrier signal. Findings The results from the experiment and simulation are in agreement showed that the MR can be switched between two states and that a change in the carrier signals amplitude can be achieved by using an MR. Thus, showing that the circuit behavior is in line with the proposed theory and validating the said theory. Originality/value In this paper, the binary signal to be modulated is modified into a suitable control signal for the MR, thus the MR relies on the internal operation of the modulator circuit for the control of its memristance. An ASK modulation can then be achieved using a floating memristor without the need for additional circuits or signals to control its memristance.