Voltage Differencing Buffered Amplifier Research Articles

Resistorless Memristor Emulators: Floating and Grounded Using OTA and VDBA for High-Frequency Applications

The design of the memristor emulator, which has found widespread of applications in analog computation, neuromorphic and biological systems, communications, etc., is much sought for. In this article, a resistorless electronically tunable grounded and floating memristor emulator by employing current-mode (CM) building blocks: operational transconductance amplifier (OTA) and voltage differencing buffered amplifier (VDBA) has been proposed. The proposed emulators can be configured as incremental and decremental operations. The robustness of the proposed emulator has been verified by performing various analyses: nonideal interpretations, process corner variations, temperature fluctuations, and nonvolatility behavior. The layout has been performed, and the theoretical fingerprint characteristics have been simulated and observed using 180-nm CMOS process parameters in the Cadence environment. The pinched hysteresis loop of the proposed memristor emulator maintains up to 5 MHz. The proposed memristor emulator uses less number of circuit components, but it maintains performance in terms of speed and operating range of frequency. Binary frequency shift keying (BFSK) has been performed using the proposed memristor to validate its functionality in the application. This memristor emulator with superior performance can be integrated into the communication system, analog computation, neuromorphic and biological systems, etc.

Voltage Differencing Buffered Amplifier (VDBA) Based Grounded Meminductor Emulator

A new meminductor emulator using a capacitor, a memristor and a voltage differencing buffered amplifier (VDBA) is proposed in this paper. This reported realization of meminductor is very simple than proposed in literature as it needs only 1 active block. The proposed emulator has been found suitable for low frequency operations with electrical tunability, and multiplier free topology. The characteristics of the proposed emulator have been verified for a frequency range of 1.8Hz to 4.9Hz using the LTspice simulation tool with 180nm CMOS technology parameters. Pinched hysteresis loops observed in flux versus current plane verifies its meminductive behavior. Moreover, the non-volatility test of the proposed emulator proves its memory behavior. The pinched hysteresis loops obtained through simulations show that the lobe area reduces with increase in frequency.

An Electronically Tunable Meminductor Emulator and Its Application in Chaotic Oscillator and Adaptive Learning Circuit

In this paper, a new design of meminductor emulator has been suggested using voltage differencing buffered amplifier (VDBA), current differencing buffered amplifier (CDBA), a resistor and two grounded capacitors. The key advantages of the proposed meminductor emulator circuits are their design simplicity, implementation without memristors and easily adjustable design for grounded/ floating decremental to incremental configurations. The proposed circuits have been designed and simulated using 180-nm process technologies in the Mentor Graphics Eldo simulation tool. The nonvolatility and Monte Carlo analysis of the proposed meminductor emulators have been given. A comparison table has also been presented to discuss the benefits of the suggested meminductor emulator designs with existing designs. The operation of the designed emulator has been corroborated by using it in the chaotic oscillator and neuromorphic circuit applications.

Low Power Squaring Circuit Using Single Voltage Differencing Buffered Amplifier

In this paper, a squaring circuit is proposed using a voltage differencing buffered amplifier (VDBA). The squaring circuit consists of a VDBA, two NMOS transistors and one resistor. The proposed structure facilitates easy cascading without any requirement of additional buffer. The behavior of the proposed structure is analyzed in the presence of nonidealities of VDBA and the corresponding mathematical formulations are also presented. The workability of the proposed circuit is verified through Cadence Virtuoso Analog Design Environment tool using 0.18[Formula: see text][Formula: see text]m generic process design kit parameters. Both pre- and post-layout simulation results have been included to confirm the functionality of the proposed circuit. The 3-dB frequency of the proposed circuit using schematic and post-layout-driven simulations is observed to be 3.77 and 3.72[Formula: see text]MHz, respectively. The power consumption of the proposed squaring circuit is found to be 110[Formula: see text][Formula: see text]W. The process, voltage and temperature (PVT) analysis has also been carried out to check the robustness of the proposed circuit. Total harmonic distortion for the entire input range is found to be less than 3%.

Voltage Differencing Buffered Amplifier-Based Novel Truly Mixed-Mode Biquadratic Universal Filter with Versatile Input/Output Features

In this paper, a first-of-a-kind mixed-mode universal filter employing three VDBAs and three passive components, is proposed. The filter operates in all four modes and provides all five filter responses, namely voltage-mode (VM), current-mode (CM), trans-impedance-mode (TIM), or trans-admittance-mode (TAM). Additionally, the same filter topology can also work as a CM single-input-multi-output (SIMO) filter. A state-of-the-art comparison of various ‘voltage differencing’ variants of the voltage differencing buffered amplifier (VDBA)-based SIMO/MISO (single-input-multi-output/multi-input-single-output)-type biquad filters further highlight the significance of the presented research. In the proposed no passive component matching is required for generating the filter responses. The filter circuit also provides inbuilt tunability of the quality factor independent of the pole frequency. The non-ideal frequency dependent gain and component sensitivity analyses of the filter were also performed. The Silterra Malaysia 0.18μm process design kit (PDK) is employed to design and validated the proposed VDBA-based filter using the Cadence design software. The simulation results closely follow the theoretical predictions. To further verify the practical feasibility of the proposed filter, an experimental evaluation is also completed. The VDBA-based filter is implemented using off-the-shelf operational transconductance amplifiers Intersil CA3080, Texas Instruments LF356 op-amp, and Analog Devices AD844s. The filter is designed for a characteristic frequency of 100 kHz. The time and frequency domain measurement results indicate the proper functioning of the filter.

Tunable Mixed-Mode Voltage Differencing Buffered Amplifier-Based Universal Filter with Independently High-Q Factor Controllability

This paper proposes the design of a mixed-mode universal biquad configuration, which realizes generic filter functions in all four possible modes, namely voltage mode (VM), current mode (CM), transadmittance mode (TAM), and transimpedance mode (TIM). The filter architecture employs two voltage differencing buffered amplifiers (VDBAs), two resistors and two capacitors, and can provide lowpass (LP), bandpass (BP), highpass (HP), bandstop (BS), and allpass (AP) biquadratic filtering responses without any circuit alteration. All passive elements used are grounded, except VM. The circuit not only allows for the electronic tuning of the natural angular frequency (ωo), but also achieves orthogonal tunability of the quality factor (Q). It also provides the feature of availability of output voltage at the low-output impedance terminal in VM and TIM, and does not require inverting-type or double-type input signals to realize all the responses. Moreover, in all modes of operation, the high-Q filter can be easily obtained by adjusting a single resistance value. Influences of the VDBA nonidealities and parasitic elements are also discussed in detail. PSPICE simulations with TSMC 0.18-µm CMOS process parameters and experimental testing results with commercially available IC LT1228s have been used to validate the theoretical predictions.

Novel VDBA based universal filter topologies with minimum passive components

In this research, voltage differencing buffered amplifier (VDBA) is utilized in designing three novel multi-input single output (MISO) topologies of universal filters. The designed filters employ minimum number of passive components and did not require any passive component matching condition. Two of the designed filters can work in dual mode of operation simultaneously. The designed filters have inbuilt tunability property. The nonideal gain analysis and sensitivity analysis of the filters are also carried out to study the effect of process variations and process spread on the filter responses. The complete layout of the VDBA is designed using 0.18μm Silterra Malaysia process design kit (PDK) in Cadence design software. The parasitic extraction is done using Mentor graphics Calibre tool. The postlayout simulations bear close resemblance with the theoretical predictions.

On the Resistorless Realization of Simulated Tunable Floating Lossy Inductors with Voltage Differencing Buffered Amplifiers

Alternative circuit designs concerning the simulation of floating lossy inductors using voltage differencing buffered amplifiers (VDBAs) are described. The topologies proposed here require only three VDBAs and one capacitor to simulate a floating inductance with series and parallel resistance. The simulated equivalent elements, namely equivalent resistance (Req) and equivalent inductance (Leq) are electronically controllable through the external bias currents of the VDBAs. The VDBA non-idealities including transconductance inaccuracy and voltage transfer error on the performance of the circuits has been discussed in detail. To support the theoretical analysis and demonstrate the practical workability of the proposed synthetic inductors, PSPICE simulation and experimental test results are also reported.

Voltage differencing buffered amplifier based low power, high frequency and universal filters using 32 nm CNTFET technology

This work presents filter applications of carbon nanotube field effect transistors (CNTFET) voltage differencing buffered amplifier (VDBA) based high frequency universal filters using 32 nm CNTFET technology of Stanford University model. CNTFETs are potential candidates to replace conventional silicon-based transistors due to their exceptional material properties. In addition, by changing chirality of carbon nanotube (CNT), the material property can be easily changed from semiconducting material to metallic. The VDBA is an active element of circuit which has high input impedance and low output impedance. These types of blocks provide an advantage for voltage mode circuits allowing cascadability and no critical component matching. The proposed CNTFET VDBA shows much higher frequency response with about 67 GHz at first stage which is well known OTA block and around 30 GHz at second stage, power consumption around 135 times less than 0.35 μm TSMC technology and 2476 times reduction in active area of chip. HSPICE and MATLAB simulation tools are used to perform all simulations.

Actively Simulated Floating Lossless Inductor for Short Range Wireless Communication

This communication describes the resistorless simulation of the floating lossless inductor using three voltage differencing buffered amplifiers (VDBAs) and one grounded capacitor. The circuit employs only a grounded capacitor, and no other extra resistor element is employed. Thus, it is suitable for further communication integrated front-end circuit design in short-range wireless and application. The realized equivalent inductance value of the simulated inductor can be changed electronically via the external biasing currents of the VDBAs. Sufficient simulation results with the PSPICE program are provided to validate the functionality of the realized inductor. In addition to establishing the practical operation of the simulator, the measured test results obtained from hardware implementation using readily available integrated chips (ICs) are also included.

Practical realization of electronically adjustable universal filter using commercially available IC-based VBDA

This paper describes the practical realization of electronically adjustable voltage-mode universal filter with three inputs and single output (TISO) using the commercially available integrated circuit (IC)-based voltage differencing buffered amplifiers (VDBAs). The realization is resistor-less and contains only two VDBAs and two capacitors. The described filter structure can realize all the five standard biquadratic filter functions from the same configuration without needing any component matching criterions. It also exhibits low-output impedance, which enables for easy cascading in voltage-mode operation. Owing to practical VDBA realization, the filter circuit can be easily made electronically tunable with orthogonal o-Q tuning. The effects of the VDBA non-idealities on the filter performance have been analyzed in detail. To prove the theoretical finding, the performance of the studied circuit was also experimentally measured using the operational transconductance amplifier

Tunable Active Grounded Lossless and Lossy Inductance Simulators with Single Grounded Capacitor Using VDBAs

In this paper, three active-C synthetic grounded inductance simulator circuits are presented, which realize tunable lossless and lossy series and parallel RL-type inductances. Each of which employs two voltage differencing buffered amplifiers (VDBAs) as active components, and a single grounded capacitor as a passive component. In all the proposed circuits, the simulated equivalent resistance and inductance values can be adjusted electronically through the transconductance gains of the VDBAs. They also do not require any critical component matching conditions and cancellation constraints. Detail non-ideal analysis including transfer errors of the VDBA has been analyzed. For circuit performance verification and comparison, some application examples are given together with computer simulation results by PSPICE program.

A low‐power voltage differencing buffered amplifier

SummaryA low‐voltage, high‐performance voltage differencing buffered amplifier (VDBA) designed using differential flipped voltage followers (DFVF) is presented in this paper. The proposed VDBA is capable of providing high transconductance and wide bandwidth (BW) with low biasing currents and buffer transfer ratio close to unity. Mathematical formulations for transconductance and buffer transfer ratio are deduced through low‐frequency small signal analysis. Pre and post layout simulations for characterization of the proposed structure are carried out on Cadence Virtuoso using gpdk 0.18‐μm CMOS process parameters. The transconductance of the proposed VDBA is observed to be varying from 411.8 μS to 1.374 mS for a corresponding bias current range of 10 to 75 μA, and the 3‐dB bandwidth (BW) is recorded to be 1.2 GHz. The PVT analysis is carried out to show the effect of process corners. To check the robustness of the proposed VDBA, Monte Carlo analysis is performed, and results have been included in the form of histograms.

Voltage Differencing Buffered Amplifier based Voltage Mode Four Quadrant Analog Multiplier and its Applications

In this paper a voltage mode four quadrant analog multiplier (FQAM) using voltage differencing buffered amplifier (VDBA) based on quarter square algebraic identity is presented. In the proposed FQAM the passive resistor can be implemented using MOSFETs operating in saturationregion thereby making it suitable for integration. The effect of non idealities of VDBA has also been analyzed in this paper. Theoretical propositions are verified through SPICE simulations at 0.18μm CMOS technology node and the simulation results are found in close agreement with theoretical values. The supply voltage is taken as ± 1V and the value of the bias current is set to 40µA.The simulated total harmonic distortion (THD) is observed to be under 3% and the total power dissipation is found as 627µW. The workability of the proposed FQAM is also tested through two applications, namely, an amplitude modulator and a rectifier. The simulated results corroborate the theoretical propositions.

Actively Floating Lossy Inductance Simulators Using Voltage Differencing Buffered Amplifiers

ABSTRACTTwo simple topologies for the simulation of floating lossy inductances are presented, which realize series and parallel RL impedances employing two voltage differencing buffered amplifiers (VDBAs) as active components. Each of the proposed circuit topologies consists of one resistor and one capacitor, which employs canonical passive components. The equivalent values of the simulated resistance and inductance can be tuned electronically by means of the external biasing currents of the VDBAs. Non-ideal gain effects of the VDBA on the proposed circuits are carried out. The performance of the proposed floating inductors is demonstrated on both a standard second-order RLC low-pass filter and a parallel resonant circuit. Laboratory experiments using commercially available ICs are included to verify the workability of the circuits. Several computer simulations with PSPICE program are also drawn together with theoretical ones for circuit performance verification.

Current and Voltage Mode Quadrature Oscillator Based on Voltage Differencing Buffered Amplifier

In this work, we present a current-mode and voltage-mode quadrature oscillator circuit using a voltage differencing buffered amplifier (VDBA), two grounded capacitors, and a grounded resistor. The oscillation condition and frequency are orthogonally (or independently) controllable. The current-mode and voltage-mode quadrature signals can be simultaneously obtained from the proposed circuit. The use of only grounded capacitors and resistors makes the proposed circuits ideal for integrated circuit implementation. The quadrature oscillator is simulated with SPICE simulation program using 0.35-µm technology parameters.

Voltage-Mode Third-Order Quadrature Sinusoidal Oscillator Using VDBAs

This paper presents a third-order quadrature sinusoidal oscillator (TOQSO) using two voltage differencing buffered amplifiers (VDBAs), three capacitors and a resistor. The new topology provides two quadrature voltage outputs. The condition of oscillation (CO) and frequency of oscillation (FO) are electronically independently controllable by the separate transconductance of the VDBAs. The workability of the proposed TOQSO is confirmed by SPICE (Version 16.5) simulation using Taiwan semiconductor manufacturing company (TSMC) 0.18 μm process parameters.