Current Differencing Buffered Amplifier Research Articles

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.

A versatile signal flow graph realization of a general transfer function by using CDBA

A general synthesis procedure is given for a versatile signal flow graph realization of a general transfer function by using current differencing buffered amplifier (CDBA). The proposed configuration uses n + 1 CDBAs, n capacitors and at most 2 n + 4 resistors. This number of resistors can be reduced to n + 1 for special cases. The circuit is eligible to obtain a variety of transfer characteristics with the same common denominator polynomial, and it is easily converted to different modes of operations. It is straightforward to find the values of the passive elements from the coefficients of the transfer function to be realized. Simulations results are obtained by using commercially available active component AD844 and CMOS technology as well. All of these make the proposed circuit attractive.

Design of a PID Controller Circuit Employing CDBAs

Proportional-integral-derivative (PID) controllers are one of the most important control elements used in the process control industry. In practice, voltage mode circuits (e.g., operational amplifiers) are largely used in analogue controllers. However, recent developments in the areas of nanotechnologies and micro-electromechanical systems (MEMS) necessitate fast operating active analogue circuits. This paper presents a PID controller circuit based on a newly introduced active universal component, so-called current differencing buffered amplifier (CDBA), and shows that the circuit performs quite well as a PID controller and offers the benefits of a current mode structure. An example is given to illustrate the application of this new active element. The development of the overall circuit relies on concepts introduced in the frequency domain, therefore it can be used as material for undergraduate-graduate circuits, systems and control courses.

Voltage-mode high-Q band-pass filters and oscillators employing single CDBA and minimum number of components

In this paper, voltage-mode second order high-Q band pass filters and oscillators which employ only single current differencing buffered amplifier (CDBA) as the active component are proposed. One of the four filter circuits and two of the four oscillators described have minimum passive component count properties, without using the internal pole of the active element. These BP filters can be easily cascaded without any recourse to impedance matching circuitry. The circuits have been analysed theoretically, simulated and experimentally tested in a laboratory. It is shown that the results of simulations and experimental work are in agreement with theoretical predictions.

Realization of multiple-output biquadratic filters using current differencing buffered amplifiers

In this paper, multiple-output multifunctional biquadratic filters using current differencing buffered amplifiers (CDBAs) as active elements are presented. The proposed circuit configuration is mainly composed of the CDBA-based cross-coupled feedback configuration and the simple CDBA-based voltage substractor. By an appropriate choice of virtually grounded passive components, the configuration can simultaneously realize lowpass, highpass, bandpass, bandstop and allpass voltage transfer functions, all at low resistance outputs. The natural angular frequency and the quality factor can orthogonally controllable. Experimental results verifying the theoretical analysis are also given.

CDBA-Based Synthetic Floating Inductance Circuits with Electronic Tuning Properties

This paper introduces two different current differencing buffered amplifier (CDBA)-based synthetic floating inductance circuits. Both configurations use a grounded capacitor. They are fully integrable and provide the advantages of electronic tuning.

Current mode multifunction filter using two CDBAs

This paper presents a cascadable current-mode (CM) multifunction biquadratic filter. The proposed circuit realizes all five different filter transfer functions employing only two current differencing buffered amplifiers (CDBAs), while previously reported CM multifunction filters require more CDBAs and more passive component count for the same number of filter transfer function realizations. Examples for different filter transfer functions are given along with the results of circuit simulations. It is shown that theoretical and simulation results are in good agreement.

NOVEL VOLTAGE-MODE UNIVERSAL FILTER USING ONLY TWO CDBAs

A novel voltage-mode universal filter employing only two current differencing buffered amplifiers (CDBAs) is proposed. The filter uses four inputs and single output to realize six responses, viz. low-pass, high-pass, inverting band-pass, noninverting band-pass, band-elimination, and all-pass through input selection with independent pole-Q control. Computer simulation results using SPICE are also given to verify the theory.

A Four Quadrant Analog Multiplier Employing Single CDBA

The author proposes a new, fully-integrable four quadrant analog multiplier using a current differencing buffered amplifier (CDBA), a new universal active element. The use of CDBA in fully-integrated multiplier circuit design is attractive, since it simplifies the implementation and reduces the component count while maintaining good performance.

Realization of nth-order current transfer function using current-differencing buffered amplifiers

The authors propose two new configurations suitable for high-order filter response. It is possible to realize the most general nth-order current-mode transfer function using these configurations, involving a single or two current-differencing buffered amplifiers (CDBAs) and the RC:–RC decomposition technique. With the proposed configurations, the number of active elements is reduced to one or two, which is a significant reduction in comparision with the previously reported methods.

A novel current-mode second-order notch filter configuration employing single CDBA and reduced number of passive components

A novel current-mode second-order notch filter configuration is proposed. The presented circuit uses single current differencing buffered amplifier (CDBA) and minimum passive components. High output impedance of the proposed filter enables the circuit to be cascaded without requiring any impedance matching device. It has also low passive sensitivities. The theoretical results are verified with PSPICE simulations.

Linearly Tunable Transconductor Using Modified CDBA

With a slight modification in current differencing buffered amplifier (CDBA), a new block, namely differential-input current feedback amplifier (DFCA), is obtained. It is shown that, with two additional MOSFETs, this modified CDBA structure can be utilized as a linearly tunable transconductor, which can also be converted to a variable-gain amplifier or an analogue multiplier.

Single resistance-controlled sinusoidal oscillators employing current differencing buffered amplifier

The basic aim of this paper is to present several of a newly introduced current differencing buffered amplifier (CDBA)-based oscillator topologies achieving orthogonal control of oscillation condition b and oscillation frequency ω0 with a reduced number of components. A single resistor is used for adjusting their frequency, and further, this resistance is grounded, which is important from the integration point of view. Taking these considerations into account they are very suitable for voltage-controlled oscillator (VCO) implementation.

A new versatile building block: current differencing buffered amplifier suitable for analog signal-processing filters

A new multi-terminal active component with two inputs and two outputs, namely current differencing buffered amplifier (CDBA) is proposed. It is derived from current feedback amplifier (CFA) which is commercially available as AD844. It has been shown by realising high-order voltage transfer function that it is beneficial to use this element as a building block to realize analog signal-processing filters.

Current-mode KHN-equivalent biquad using CDBAs

A new Kerwin-Huelsman-Newcomb (KHN)-equivalent biquad, operating in the current mode (CM), is proposed. The proposed circuit is derived from the adjoint graph of the signal flow graph corresponding to the classical KHN circuit. The derived circuit is a CM universal filter, which offers all the main advantages of CM circuits as well as those of the classical KHN circuit. The proposed circuit employs three current differencing buffered amplifiers (CDBAs) as active elements. In addition to the three basic filter responses, it also allows the realisation of the notch and allpass responses without requiring any element matching conditions.