Current Differencing Buffered Amplifier Research Articles

New canonic lossy inductor using a single CDBA and its application

A new lossy inductor (parallel R-L type) using single current differencing buffered amplifier (CDBA) is presented, which employs only two resistors and a grounded capacitor. The proposed lossy inductor is shown to be useful in realizing an oscillator circuit, which provides quadrature voltage outputs using only two CDBAs, three resistors and two grounded capacitors and offers independent control on condition of oscillation and frequency of oscillation up to a frequency of 61 MHz. Detailed non-ideal analysis including single-pole model for voltage and current gain has also been carried out. SPICE simulation results and experimental results based upon the CDBA constructed from commercially available IC AD844 have been included which confirm the practical workability of the proposed lossy inductor and quadrature oscillator circuit.

Single CDBA Based Voltage Mode Bistable Multivibrator and Its Applications

In this paper, current differencing buffered amplifier (CDBA) based bistable multivibrators are introduced. Each presented circuit is constructed using single CDBA as the basic active building block and three resistors. Two applications namely an astable and a monostable multivibrator are also realized to demonstrate the usefulness of the proposed bistable multivibrators. The presented circuits are simulated using PSPICE from Cadence Orcad16.2 to verify their functionality. Simulation results agree well with the theoretical analysis.

New Multiplier/Divider Using a Single Cdba

A new multiplier-divider circuit using a single Current Differencing Buffered Amplifier (CDBA) and only six MOSFETs has been presented. The proposed circuit has the advantage of simultaneously realizing a multiplier and divider without changing the circuit topology. The basic functions of the proposed circuit have been verified through PSPICE simulations using a CMOS CDBA and NMOS transistors with process parameters of 0.35 µm CMOS technology and some application results of the proposed cell in various modes of operation have been included.

Voltage Mode Astable Multivibrator Using Single CDBA

This paper aims at presenting three voltage mode square wave generator circuits using single current differencing buffered amplifier (CDBA), a recently proposed mixed mode building block. The first proposed circuit produces a variable frequency output having fixed duty cycle, whereas the rest of the circuits have variable duty cycle. One of the circuits uses passive element adjustment to control the duty cycle, whereas electronic control is used in the other circuit. The workability of the proposed circuits is confirmed through SPICE simulations and experimental work.

New Voltage Mode Universal Filters Using Only Two CDBAs

Two new configurations for voltage mode universal filters (VMUFs) using only two current differencing buffered amplifiers (CDBAs) are proposed. Both of the new configurations can realize all the five standard types of the filters, namely, low pass (LP), high pass (HP), band pass (BP), band stop (BS), and all pass (AP), from the same topology. In contrast to previously known CDBA-based VMUFs, the new configurations do not need an additional active device for voltage inversion to realize all pass functions. The proposed configurations offer the tunability of the natural angular frequency(ωo), quality factor(Q), or the bandwidth (BW) through separate virtually grounded resistors. Moreover, both circuits have resistive input impedance (which can be made high) and a low output impedance to facilitate easy cascading without additional buffers. PSPICE simulation results, based upon commercially available AD844 ICs to implement the CDBA, are included which confirm the practical workability of the new VMUF configurations.

Selective Filters and Tunable Sinusoid Oscillator Using a CDBA

The realization of some new selective filters using single current differencing buffered amplifier (CDBA) and few RC components is presented. The same topology provides lowpass (LP), bandpass (BP) and highpass (HP) characteristics with appropriate choice and location of the RC components in the circuit. Incorporation of a suitable feedback loop through a voltage buffer unity-gain cell yields a tunable sinusoid oscillator. Effects of the device port mismatch errors (ε) and parasitic z-node capacitance (Cz) of the CDBA element are shown to be insignificant and corresponding sensitivities are extremely low. Satisfactory experimental verifications of the filter quality (Q) and oscillator tuning range (500 KHz ≤ fo ≤ 5 MHz) are carried out.

Voltage Mode Universal Filter Using Current Differencing Buffered Amplifier as an Active Device

Integrated filter circuit design resulted in desire for replacement of Inductors by active elements like Operational Amplifiers which led to the introduction of active filters. Active filter design has evolved over a period of time. Starting with OP AMPs, we have witnessed phenomenal growth of active component usage in filter design and development catering to varying requirements. This has contributed greatly in emergence of circuits with minimal limitations and advantages in terms of wide Bandwidth and High slew rates. Current Differencing Buffered Amplifier (CDBA) based active filter design has resulted in introduction of many novel circuits .This paper proposes a new Voltage-mode three input and Single output (TISO) multifunction filter based on single CDBA, four resistors and two capacitors. This second order filter circuit is capable of realizing various filter functions by choosing values of the three inputs variably. The natural frequency (ω0) can be tuned with passive components and the Q of the circuit is independent of (ω0) .The higher cascading capability of the circuit is ensured because of its low - output impedance. Further PSPICE-simulated results are in conformity with theoretical values.

Pathological realizations of the DCVC (CDBA) and applications to oscillators and filters

The historical origin of the introduction of the differential current voltage conveyor (DCVC) also known as the current differencing buffered amplifier (CDBA) is reviewed. Pathological realizations of the modified differential current conveyor (MDCC) and of the DCVC are given. Generation of alternative equivalent oscillator and filter circuits using voltage followers (VF), current followers (CF), voltage inverters (VI) and current inverters (CI) from known CDBA oscillators and filters is demonstrated by several examples. It is found that there is duplication in some of the recently published circuits and new simplified oscillator and filter circuits are reported.

CMOS‐controlled inverting CDBA with a new all‐pass filter application

AbstractIn this study, new active elements called inverting current differencing buffered amplifier (ICDBA) and current‐controlled ICDBA (C‐ICDBA) are presented. Unlike current differencing buffered amplifier (CDBA), their voltage transfer ratio between the Z and W terminals are equal to minus one. Furthermore, CMOS implementations of the C‐ICDBA and current‐controlled CDBA (C‐CDBA) are shown. Moreover, a novel first‐order all‐pass filter is proposed to show advantages and new circuit producing capability of the ICDBA/C‐ICDBA. Lastly, an electronically tunable band‐pass filter is given as an application example using the presented all‐pass filter. The measured and simulation results are in good agreement with the theoretical ones. Copyright © 2010 John Wiley & Sons, Ltd.

Design of CDBA-based active polyphase filter for low-IF receiver applications

A novel first-order active-RC polyphase filter section, using current differencing buffered amplifiers (CDBAs), is presented. The section uses 6 resistors, 2 capacitors, and 2 CDBAs. The transfer function of the proposed section has a single pole and optionally a single zero. Increasing the number of cascading sections, any higher order polyphase filter can be realized. This paper also introduces the leakage caused by element deviation and the effects of the amplifier in nonideal cases. Furthermore, nonideal performances of the proposed filter section are tested with PSpice simulations.

Systematic realisation of quadrature oscillators using current differencing buffered amplifiers

A systematic approach is presented to realise quadrature oscillators using current differencing buffered amplifiers (CDBAs). Based on a general scheme employing a cascade of a special type of low-pass filter and an integrator in a closed loop, a general configuration is formulated that yields 12 single-resistor-controlled-quadrature oscillator circuits using CDBAs an active elements. All the oscillator circuits enjoy fully uncoupled independent control of condition of oscillation and frequency of oscillation using a minimum possible number of active components, grounded/virtually grounded capacitors and grounded/virtually grounded resistors. PSPICE simulation results along with hardware experimental results, based on commercially available AD844 ICs to construct the CDBAs, are included which confirm the practical workability of the new quadrature oscillator configurations.

NEW REALIZATIONS OF VOLTAGE-MODE QUADRATURE OSCILLATORS USING CURRENT DIFFERENCING BUFFERED AMPLIFIERS

A number of sinusoidal oscillators using current differencing buffered amplifiers (CDBAs) have been reported in the literature. However, only three of them are canonic quadrature oscillators (i.e., requiring two capacitors). The aim of this letter is to present additional realizations of single/dual-resistance-controlled quadrature oscillators using CDBAs. Four voltage-mode quadrature oscillators are proposed, which provide the following advantageous features: (i) use of reduced and canonic component count, viz. two CDBAs, three/four resistors and two capacitors, (ii) all passive components are grounded or virtually grounded, which is favorable from integration point of view and (iii) independent and non-interactive resistor control of the condition of oscillation (CO) and the frequency of oscillation (FO). Simulation results verifying the workability of the proposed circuits have been included.

Active-R tunable integrators using a current differencing buffered amplifier

Some new active-R integrator realisation schemes using the transadmittance pole of a current differencing buffered amplifier (CDBA) element are presented. The time constant (τ) is tunable by a single resistor whereas the integrator quality factor (Q) can be made very large with suitable realisability design. The active sensitivities of τ and Q are extremely low. As an application, a variable frequency sinusoid oscillator utilising the integrators in a loop has also been designed. Practical results using the hardware implementation and by PSPICE macromodel simulation are included for a frequency range of 1 MHz < f < 24 MHz.

Low voltage low power CMOS current differencing buffered amplifier

The major goal of this work is to present a new CMOS realization for the current differencing buffered amplifier (CDBA). A design technique based on flipped voltage follower current sources is preferred to obtain a high performance CDBA. The proposed circuit can operate with the minimum supply voltages of ±0.6 V. It also consumes less power than its counterparts that have been reported so far. Moreover, the proposed CDBA has good voltage and current gain accuracies. For the simulations, UMC 0.18 μm CMOS process is used. The performance of the CDBA is verified with HSPICE. Finally, a second-order, allpass/notch filter configuration is proposed to show the performance and usefulness of the circuit. The results from HSPICE simulations are in remarkable agreement with the expected ones.

Comment on “Voltage-Mode All-Pass Filters Including Minimum Component Count Circuits”

This comment is related to the recently published article “Active and Passive Electronic Components” by S. Maheshwari (2007), which presents single current differencing buffered amplifier (CDBA) and current-controlled current differencing buffered amplifier- (CC-CDBA-) based first-order voltage-mode (VM) all-pass filtering (APF) sections. The paper is reviewed, and additional first-order APF realizations have been proposed.

Electronically Tunable Dual-Input Integrator Employing a Single CDBA and a Multiplier: Voltage Controlled Quadrature Oscillator Design

A new dual-input differential input active integrator using a current differencing buffered amplifier (CDBA) is proposed. A multiplier element is appropriately used in the circuit whose control voltage (Vc) tunes the integrator time constant (τ) electronically. The design of a voltage controlled quadrature oscillator (VCQO) based on the proposed integrator had been satisfactorily implemented. A new type of measurement for the tuning error of the oscillator based on the Nyquist plot is presented that shows an error of only 2% atfo≈1 MHz with Total Harmonic Distortion (THD) less than 3%.

Third order lowpass Butterworth filters using unity gain current amplifiers

Some new realizations of third order lowpass (LP) Butterworth filters using the current differencing buffered amplifier (CDBA) and current feedback amplifier (CFA) type unity gain cells are presented. The circuits are practically active insensitive to the decvice port tracking errors (e). Effects of the device parasitic capacitances on the nominal design are insignificant which can be conveniently compensated. With suitable design alternate bandpass (BP) Butterworth characteristics may also be obtained.

Single-resistance-controlled quadrature oscillator using current differencing buffered amplifiers

A single-resistance-controlled quadrature oscillator circuit using current differencing buffered amplifiers (CDBAs) as active components is proposed. The proposed circuit is realised through the employment of two CDBAs, three resistors and two grounded capacitors. Outputs of two sinusoidal with 90° phase difference are available. The oscillation condition and the oscillation frequency of the proposed quadrature oscillator can be controlled independently by a single resistor. In comparison with the previously reported circuits, the proposed configuration considerably reduces the number of passive elements.

CDBA-Based Universal Biquad Filter and Quadrature Oscillator

The voltage-mode universal biquadratic filter and sinusoidal quadrature oscillator based on the use of current differencing buffered amplifiers (CDBAs) as active components have been proposed in this paper. All the proposed configurations employ only two CDBAs and six passive components. The first proposed CDBA-based biquad configuration can realize all the standard types of the biquadratic functions, that is, lowpass, bandpass, highpass, bandstop, and allpass, from the same topology, and can also provide orthogonal tuning of the natural angular frequency(ωo)and the bandwidth (BW) through separate virtually grounded passive components. By slight modification of the first proposed configuration, the new CDBA-based sinusoidal quadrature oscillator is easily obtained. The oscillation condition and the oscillation frequency are independently adjustable by different virtually grounded resistors. The sensitivity analysis of all proposed circuit configurations is shown to be low. PSPICE simulations and experimental results based upon commercially available AD844-type CFAs are included, which confirm the workability of the proposed circuits.

Low-voltage NMOS-based current differencing buffered amplifier and its application to current-mode ladder filter design

An integratable circuit technique to realize a low-voltage current differencing buffered amplifier (CDBA) is introduced. The realization scheme is through the modification of a low-input resistance CCII+ and the proposed CDBA can operate with the minimum supply voltage of ±1.25 V. In order that the signal path consists of only NMOS transistors, a negative current mirror using NMOS transistors is employed. With standard 0.5 µm CMOS process parameters, PSPICE simulation results show that the proposed CDBA provides the terminal resistance of , , and the −3 dB bandwidth of about 500 MHz. Application examples employing the proposed CDBA as active elements in the leapfrog simulation of current-mode ladder filters are also included.