Aslihan Kartci

An Additional Approach to Model Current Followers and Amplifiers with Electronically Controllable Parameters from Commercially Available ICs

Several behavioral models of current active elements for experimental purposes are introduced in this paper. These models are based on commercially available devices. They are suitable for experimental tests of current- and mixed-mode filters, oscillators, and other circuits (employing current-mode active elements) frequently used in analog signal processing without necessity of onchip fabrication of proper active element. Several methods of electronic control of intrinsic resistance in the proposed behavioral models are discussed. All predictions and theoretical assumptions are supported by simulations and experiments. This contribution helps to find a cheaper and more effective way to preliminary laboratory tests without expensive on-chip fabrication of special active elements.

New Double Current Controlled CFA (DCC–CFA) Based Voltage–Mode Oscillator with Independent Electronic Control of Oscillation Condition and Frequency

In this paper, a new electronically tunable quadrature oscillator (ETQO) based on two modified versions of current feedback amplifiers (CFAs), the so called double current controlled CFA (DCC-CFAs) is presented. The frequency of oscillation (FO) of the proposed voltage-mode (VM) ETQO is electronically adjustable by current gain or by varying the intrinsic resistance of the X terminal of the active element used. The condition of oscillation (CO) is adjustable by current gain independently with respect to frequency of oscillation. Simultaneous control of current gain and intrinsic resistance allows linear control of FO and provides extension of frequency tuning range. In the proposed circuit all the capacitors are grounded. The use of only grounded capacitors makes the proposed circuit ideal for integrated circuit implementation. The presented active element realized by using BiCMOS technology and the behavior of proposed circuit are discussed in details. The theoretical results are verified by SPICE simulations based on CMOS ON-Semi C5 0.5 μm and bipolar ultra high frequency transistor arrays Intersil HFA 3096 process parameters.

Application possibilities of VDCC in general floating element simulator circuit

In this study, a low-voltage design of a new general floating element simulator circuit for realizing floating frequency dependent negative resistor (FDNR), floating inductor (FI), floating capacitor (FC), and floating resistor (FR) simulator, depending on the selection of passive circuit elements, is described. The circuit employs two voltage differencing current conveyors (VDCCs) at low voltage levels (±0.45 V) and three passive components. It does not require any passive element matching. Moreover, the new general floating element simulator can be electronically controllable by changing the bias currents of the VDCCs or can be controlled through the grounded resistor or capacitors. Finally, using one of the described floating element simulator, i.e. FDNR, a fourth-order Butterworth characteristic band-pass filter is simulated via PSPICE using 90 nm, level 7 PTM CMOS technology parameters. The simulations agree with the theoretical analysis.

Comparative Study of Discrete Component Realizations of Fractional-Order Capacitor and Inductor Active Emulators

Due to the absence of commercially available fractional-order capacitors and inductors, their implementation can be performed using fractional-order differentiators and integrators, respectively, c...

Quadrature oscillator solution suitable with arbitrary and electronically adjustable phase shift

This paper discusses new quadrature oscillator consisting of two all-pass sections and inverting amplifier that is capable of generating two signals with arbitrary phase shift between them. Constrains and limits of this simple idea are discussed. Verifications of theoretical expectations were provided by Spice simulations based on active devices with TSMC 0.18 μm NMOS and PMOS technological models.

Application of Numerical Inverse Laplace Transform Methods for Simulation of Distributed Systems with Fractional-Order Elements

The paper presents a computationally efficient method for modeling and simulating distributed systems with lossy transmission line (TL) including multiconductor ones, by a less conventional method. The method is devised based on 1D and 2D Laplace transforms, which facilitates the possibility of incorporating fractional-order elements and frequency-dependent parameters. This process is made possible due to the development of effective numerical inverse Laplace transforms (NILTs) of one and two variables, 1D NILT and 2D NILT. In the paper, it is shown that in high frequency operating systems, the frequency dependencies of the system ought to be included in the model. Additionally, it is shown that incorporating fractional-order elements in the modeling of the distributed parameter systems compensates for losses along the wires, provides higher degrees of flexibility for optimization and produces more accurate and authentic modelling of such systems. The simulations are performed in the Matlab environment an...

Novel grounded capacitor-based resistorless tunable floating/grounded inductance simulator

This paper deals with resistorless lossless floating/ grounded inductance simulator and its application to third-order voltage-mode elliptic low-pass and band-pass filters providing high linearity and wide bandwidth in high frequencies. The inductance simulator circuit consists of only one grounded capacitor, single dual-output current follower (CF±), and one high-performance and versatile active element so-called voltage differencing inverting buffered amplifier (VDIBA), employing ten and six transistors, respectively. The resulting equivalent inductance value of the proposed simulator can be electronically adjusted via change of input intrinsic resistance of CF± and/or by means of bias current of the internal transconductance of the VDIBA. Theoretical results are verified by SPICE simulations using T SMC 0.18 μm level-7 LO EPI SCN018 CMOS process parameters with ±0.9 V supply voltages.

Electronically tunable VDCC-based floating capacitance multiplier

In this paper a new grounded capacitance multiplier using two Voltage Differencing Current Conveyors (VDCCs), two resistors, and one grounded capacitor is presented. The proposed capacitance multiplier can be tuned electronically by changing the biasing current of the VDCC. Moreover, the circuit does not require any conditions of component matching. The performance of the proposed capacitance multiplier is verified, and simulated by using PSPICE with TSMC CMOS 0.18 μm process parameters.

Modulator based on electronic change of phase shift in simple oscillator

In this study, we propose phase shift keying system using an oscillator based on two all-pass filters. The main idea is based on phase commutation by converted data to two pairs of DC control voltages for controlling both all-pass sections. Therefore, the proposal of converter of data to DC control voltages is solved with precise amplitude automatic gain control circuit. The system operation was verified while employing commercially available devices through PSPICE program at the modulation frequencies 1 MHz and 10 kHz with driving signals 0 V (L) and 5 V (H), respectively. The simulation results confirmed the theoretical presumptions.

Importance of amplitude stability and spectral purity of produced signals in a quadrature oscillator

This paper presents two solutions for an amplitude automatic gain control circuit implemented in a simple second-order quadrature oscillator based on the non-inverting band-pass filtering response and a block with positive feedback with controllable gain or intentional nonlinearity. The results regarding amplitude stability, total harmonic distortion, available tunability range, time required to obtain stable oscillations, etc. are discussed and both AGC solutions are compared. PSpice software was used for verification in simulations.