Voltage Differencing Transconductance Amplifier Research Articles

Fractional quadrature oscillator using VDTAs with grounded capacitors

In this proposed work, the fractional order quadrature oscillator using voltage differencing trans-conductance amplifier (VDTA) as an active building block is designed. The circuit configuration of VDTA with its characteristics is shown. The expression for the frequency of oscillation is derived. The non-ideal effects and sensitivity of the proposed design for the parasitic components are determined. The stability of the proposed work is analyzed with the help of value and the location of roots of the proposed circuit. The approximation of the fractional order capacitor is done with the help of a single parallel circuit of passive components and General impedance converter. The comparison of the proposed work is done with the existing works. The results of the proposed work are verified using PSPICE with TSMC CMOS 180 nm technology.

Single VDTA-Based Tunable Floating Lossy Inductance Simulation Circuits

In this study, two circuit topologies for simulating tunable lossy floating inductors are proposed. In each design, the simulators make use of a single voltage differencing transconductance amplifier (VDTA), and only two passive elements with a grounded capacitor. The proposed active inductance simulators do not need some kind of component matching conditions and cancellation constraints for the desired realization. Besides, the simulated equivalent resistance and inductance values are independently tunable through a single resistor and/or the transconductances of the VDTA. The workability of all the proposed circuits is well accomplished through PSPICE simulations and experimental test results. To ascertain the feasibility of the proposed inductor designs, they are used to construct a fourth-order equal-ripple (3-dB) lowpass filter and an electronically tunable sinusoidal oscillator.

New floating/grounded FDNC and non-ideal grounded FDNR simulators based on VDTA

The paper proposes a new grounded/floating frequency dependent negative conductance (FDNC) simulator, and a non-ideal frequency dependent negative resistance (FDNR) simulator, based on deployment of voltage differencing transconductance amplifiers (VDTA), along with two grounded capacitances. The presented simulators feature electronic controllability of realized negative conductance/resistance via DC bias current of VDTA, with no component matching constraints. The non-ideality analysis of the circuits is also presented. The proposed solutions exhibit an excellent behaviour under non-ideal conditions with low active/passive sensitivity. The working of the presented simulators has been verified by corresponding voltage mode filter design examples, and has been verified by HSPICE simulations which were carried out on the basis of 0.18 μm CMOS technology.

Design and experimentation of VDTA based oscillators using commercially available integrated circuits

With the focus of employing single Voltage Differencing Transconductance Amplifier (VDTA) in designing of electronically tunable oscillators, three configurations have been proposed in this manuscript. Each configuration enjoys an efficient integrated circuit implementation due to use of grounded capacitors. Unambiguous and independent control of its condition and frequency of oscillation is an additional feature which is available in all the configurations along with the quadrature outputs in voltage mode. The designed configurations have been tested both through simulation and experimental setup employing a newly proposed hardware arrangement of VDTA designed using off the shelf IC, i.e., OPA860. Moreover, the oscillators have also been experimentally justified with already available hardware realization of VDTA. Experimentation results generated using two different ICs, with two different hardware setups, have been tabulated so as to provide an illustrative study of the performances of oscillators.

Voltage Differencing Transconductance Amplifier based Ultra-Low Power, Universal Filters and Oscillators using 32 nm Carbon Nanotube Field Eff ect Transistor Technology

Carbon nanotube field effect transistor (CNTFET) is strong candidate to replace existing silicon based transistors. The ballistic transport of electrons in CNTFET channel leads to ultra-low power or high frequency devices. Since, lot of digital applications of CNCTFET were presented. However, much less work was done in analog applications of CNTFETs. This paper presents analog applications of CNTFET and CNTFET implementation of voltage differencing transconductance amplifier (VDTA). The CNTFET VDTA based filters and oscillators were proposed. The VDTA circuits are resistorless and can be tuned electronically only by changing transconductance. The proposed CNTFET VDTA show power consumption of 15000 times less than compared to 0.18um TSMC technology and significant reduction in chip area. All simulations were performed using HSPICE and MATLAB simulation tools.

Systematic Synthesis of Compressive VDTA-Based T-T Filter with Orthogonal Control of f o and Q

Based on sixteen nullor-mirror models of the voltage differencing transconductance amplifier (VDTA) and port admittance matrices of the tow-Thomas (T-T) filter with orthogonal control between the characteristic frequency (fo) and figure of merit (Q), two different categories of the voltage-mode and transconductance-mode T-T filters are synthesized by the means of the nodal admittance matrix (NAM) expansion method. The category A filter that employs two compressive VDTAs and two grounded capacitors includes four structures, and the category B filter that uses two compressive VDTAs, two grounded capacitors, and one grounded resistor, also includes four structures. These circuits are suitable for integrated circuit manufacture, and their parameters fo and Q can be orthogonally adjusted with varying the bias currents of VDTAs. After the paper and pencil test is completed, the computer analyses, including alternating current (AC), parameter sweep, Monte Carlo (MC), and noise analyses, are performed to support the synthesis approach.

Implementation of chaotic oscillator by designing a simple Chua’s diode using a single VDTA

A simple Chua’s chaotic oscillator circuit using voltage differencing transconductance amplifier (VDTA) is presented in this paper. The circuit is implemented by designing a straightforward and compact Chua’s diode using only one VDTA and one resistor. The proposed chaotic oscillator offers the advantages of low component count and increases the frequency spectrum having a dominant frequency in the range of tens of MHz. It is simulated in Pspice using both macro model of commercially available operational transconductance amplifier (OTA) integrated circuit MAX435, and 0.18 µm CMOS TSMC Technology parameters. The simulated chaotic responses at different nodes and the various attractors are observed conforming to the theoretical predictions. The responses with a dominant operating frequency of 20 MHz is shown, which is much higher than the earlier implementations of Chua’s circuit. The power consumption of the circuit is found as 0.243 mW. The workability of the circuit is also verified experimentally on a breadboard by assembling VDTA using MAX435. Non-ideality analysis has also been carried out in detail. Finally, the paper concludes with the comparison of various aspects with the earlier implementations.

Improved current-mode wave active filter

ABSTRACT In this paper, a resistorless improved wave active filter (WAF) is presented using a comparatively new current-mode building block, namely extra X current-controlled current conveyor (EX-CCCII). The proposed wave active filter is designed in the current mode. The incident and reflected waves are used for designing the basic wave active elements, namely series and shunt inductors (L) and capacitors (C). The novelty of the circuit is that the mathematical operations like lossy integrator, unity gain amplifier, summation, and subtraction, required to realise the wave active elements, are accomplished by judiciously using the port relationships of EXCCCII. As a result of which the proposed circuit is compact and uses only two EXCCCIIs and one grounded capacitor for the realisation of wave elements (L and C). One 3rd and one 4th order Butterworth wave active filters are designed using EX-CCCII-based wave elements and simulated in cadence using 0.18 µm TSMC CMOS technology. The comparison indicates that the proposed WAF uses minimum numbers of analog building blocks (ABBs) and consumes the least power; moreover, the performances such as noise, percentage total harmonic distortion (%THD), and electronic controllability of cut-off frequency of the filters are also reported. Abbreviations: ABB: analog building block; FDNR: frequency-dependent negative resister; WAF: wave active filter; THD: total harmonic distortion; OTA: operational transconductance amplifier; CFOA: current feedback operational amplifier; VDTA: voltage differencing transconductance amplifier; OTRA: operational transresistance amplifier; CCDDCCTA: current-controlled differential difference current conveyor transconductance amplifier; DVCCCTA: differential voltage current-controlled conveyor transconductance amplifier; DVCCTA: differential voltage current conveyor transconductance amplifier; EX-CCCII: extra X current-controlled conveyor

Electronically Tunable VDTA-Based Multi-function Inverse Filter

An electronically tunable realization of voltage differencing transconductance amplifier (VDTA)-based multi-function inverse filter circuit is proposed in this letter. Various responses namely inverse low pass, inverse high pass, inverse band pass, and inverse band reject are achieved through switch settings. The proposed circuit uses only grounded capacitors and adds electronic tunability to filter parameters through bias currents of VDTA. SPICE simulations using TSMC 180 nm CMOS technology parameter are carried out to examine operation, total harmonic distortion and noise performance of proposal. Monte Carlo simulations are performed to study performance of the proposal under simultaneous variation in passive component values, oxide thickness and transistor threshold voltage.

Flux Controlled Floating Memristor Employing VDTA: Incremental or Decremental Operation

This research article offers a floating memristor model using single voltage difference transconductance amplifier (VDTA) and grounded passive components. The proper utilization of VDTA port characteristics with passive components exhibits both incremental and decremental modes of operation without multiplier circuit. The performance analysis of proposed memristor is verified by using post layout Cadence Virtuoso simulation to examine the characteristics of all possible temperature and process Corners. In addition, experimental verification of VDTA-based memristor is done using commercially available operational transconductance amplifier (OTA) as IC CA3080. The results obtained through simulation and experiment follows the theoretical aspects. Moreover, an application perspective of the proposed design includes a brief neuromorphic circuit implementation for Pavlovian associative learning experiment.

CMOS Realization of VDTA Based Electronically Tunable Wave Active Filter with Minimum Power Consumption at Low Supply Voltage ±0.82 V

This paper presents a higher order voltage and current mode low pass or high pass filter for wave active filter based on Voltage Differencing Transconductance Amplifiers (VDTAs). The wave equivalent variable technique and topological simulation as well as operational realization using wave variables techniques are proposed for basic active building blocks of wave active filters. The proposed wave equivalent technique is employed for wave active filter with the proper selection of the terminal connections. This work presented the basic element for the realizing wave active filter is the series inductor with parallel grounded capacitor. The proposed wave active filter is verified by realizing a 4th order low pass and high pass Butterworth filter with minimum power consumption at ±0.82 V using SPICE simulation with 0.18 μm TSMC CMOS technology parameters.

Schmitt Trigger Circuits using Various Active Devices

A vast number of diverse analog circuit blocks have been arosed in the past few decades. A various active devices are Operational Amplifier (Op-Amp), Current Conveyor (CC), Operational Transconductance Amplifier (OTA), Differential Difference Current Conveyor (DDCC), Differential Difference Current Conveyor Transconductnace Amplifier (DDCCTA), Z-Copy Current Differencing Transconductance Amplifier (ZC-CDTA), Voltage Difference Transconductance Amplifier (VDTA) and so on. A review on Schmitt trigger circuits by using different active devices are presented in this paper since Schmitt trigger circuits are widely used in numerous applications such as in waveform generators, wave-shaping circuits, comparators, Bio-medical applications, analog processing systems, communication and instrumentation systems.

Schmitt Trigger Circuits using Various Active Devices

A vast number of diverse analog circuit blocks have been arosed in the past few decades. A various active devices are Operational Amplifier (Op-Amp), Current Conveyor (CC), Operational Transconductance Amplifier (OTA), Differential Difference Current Conveyor (DDCC), Differential Difference Current Conveyor Transconductnace Amplifier (DDCCTA), Z-Copy Current Differencing Transconductance Amplifier (ZC-CDTA), Voltage Difference Transconductance Amplifier (VDTA) and so on. A review on Schmitt trigger circuits by using different active devices are presented in this paper since Schmitt trigger circuits are widely used in numerous applications such as in waveform generators, wave-shaping circuits, comparators, Bio-medical applications, analog processing systems, communication and instrumentation systems.

A VDTA-based robust electronically tunable memristor emulator circuit

In this paper, a fully-integrated tunable grounded memristor emulator circuit based on voltage differencing transconductance amplifier (VDTA) has been proposed. The proposed memristor emulator circuit utilizes two VDTA active building blocks, two grounded resistors, a grounded capacitor and a four-quadrant analog multiplier. The working concept along with the detailed derivation of the mathematical model of the circuit has been discussed numerically and analytically to validate the operation of the proposed emulator. The operations of the proposed emulator circuit, as governed by the established model, have been verified by performing simulations in Cadence Virtuoso at 45 nm technology node. Robustness analyses performed, reveal significant process-variation tolerance at deep sub-micron technology node.

High Frequency Meminductor Emulator Employing VDTA and its Application

This research article comes with a grounded as well as floating meminductor using voltage difference transconductance amplifier (VDTA). The proposed meminductor models have only two active VDTA and grounded capacitors each. The performance evaluation of the proposed meminductor is verified using post-layout simulation in the Cadence Virtuoso tool and experimentally using off the self component such as operational transconductance amplifier (OTA) for the implementation of VDTA with passive components. Moreover, neuromorphic circuit implementation as an application of the proposed meminductor is well incorporated in this literature.

Synthesis Approach for Compact VDTA Quadrature Sine-Wave Oscillators with Orthogonal Control

From the nodal admittance matrix (NAM) expansion approach and 16 pathological patterns of the voltage differencing transconductance amplifier (VDTA), two different categories, namely sort A and sort B, of the quadrature sine-wave oscillators-employed VDTAs and grounded capacitors in the current mode are synthesized. In all, four quadrature sine-wave oscillators with two sets of quadrature current outputs are attained. Because canonic number is used for component quantity, the oscillators are appropriate to integrated circuit realization and also provide electronic, linear, and orthogonal adjustments between the oscillation criterion and frequency by means of tuning bias currents of the VDTAs. The paper-and-pencil and simulation analyses as well as experimental analysis have been carried out to check the utilized synthesis approach.

Linearly Tunable CMOS Voltage Differencing Transconductance Amplifier (VDTA)

This paper proposes an alternative way to implement the CMOS voltage differencing transconductance amplifier (VDTA) with linearly tunable. It has been designed by using the floating current source (FCS) and the current squaring circuit. The circuit achieves its linear tunability by squaring the long-tail biasing current of the FCS. In this way, the transconductance gains of the proposed CMOS VDTA can be varied linearly through adjusting the DC bias currents. As an application example, the proposed VDTA is used in the design of an actively tunable voltage-mode multifunction filter. The derived filter possesses the following desirable properties: simultaneous realization of three standard filter functions; employment of only two grounded capacitors; and electronic tunability of w o and Q . The performance of the proposed circuit and its filter design application were examined by PSPICE simulations with TSMC 0.25- m m CMOS real process technology.

A Novel Simple Differentiator Circuit Based on Carbon Nano Tube Field Effect Transistors Voltage Difference Transconductance Amplifier

: This paper brings in a new design, namely, voltage mode differentiator with an active element, Carbon Nanotube Field Effect Transistors Voltage Difference Transconductance Amplifier (CNVDTA). The circuit thus proposed needs one Carbon Nanotube Field Effect Transistors Voltage Difference Transconductance Amplifier (CNVDTA) element and a single capacitor. While fabricating IC’s in VLSI design, the proposed circuit proves more adaptable and applicable with the anticipated results. Methods: The proposed CNVDTA based voltage mode differentiator in CNFET technology was simulated at 32 nm at a voltage supply of ±0.9 V using the Cadence Virtuoso CAD tool. Results: It is also reported that the proposed circuit would function with ±0.9 V supply voltage and would also take care of the bias current of the order of 150 µA. Further, on the part of the transconductance (gm), it is electronically tunable with the help of bias current. Conclusion: The CNVDTA based differentiator has been found to be very useful in the triggering circuit of CRO’s, wave shaping circuits, power control circuits etc. It is also found useful in detecting the high-frequency components in the input signals.

Realization of Resistorless and Electronically Tunable Inverse Filters Using VDTA

This paper presents resistorless realization of inverse filters using voltage differencing transconductance amplifier (VDTA). First, four topologies are proposed which provide inverse low-pass, high-pass, band-pass, and band-reject responses. Subsequently, a unified inverse filter is also derived by incorporating two switches in the combination of proposed inverse low-pass and inverse band-pass topologies. This topology is capable of providing inverse low-pass, inverse high-pass, inverse band-pass, and inverse band-reject responses by appropriate switch settings. The proposed inverse filter structures are electronically tunable and use only grounded capacitors. The behavior of the proposed filters is also investigated for nonidealities. To verify the functionality of the proposed inverse filter circuits, SPICE simulation is carried out using 0.18-[Formula: see text]m CMOS technology parameters from TSMC. The effect of deviation in the active and passive component values on angular frequency is tested through Monte Carlo simulation.

Voltage differencing transconductance amplifier based fractional order multiple input single output universal filter

In this paper a Voltage Differencing Transconductance Amplifier (VDTA) based Voltage Mode (VM) Multi Input Single Output (MISO) Fractional Order filter (FOF) providing all five filter responses is presented. The proposed FOF is designed using single VDTA and two fractional Capacitors (FC). The FC is implemented using RC ladder network; component values of which are computed using Carlson rational approximation. For illustration, FC of 0.5 order has been implemented using first, second and third iterations of Carlson approximation, which results in different integer order approximation functions. The ladder component values for all iterations are computed using MATLAB. The effect of different iterations on FOF behavior is also studied. The proposed FOF is verified through Cadence Virtuoso simulations using 0.18 µm CMOS technology.