In the paper, an analysis of the state-of-the-art of active elements for analog signal processing is presented which support - in contrast to the conven tional operational amplifiers - not only the voltage-mode but also the current- and mixed-mode operations. Several pro blems are addressed which are associated with the utiliza tion of these elements in linear applications, particularly in frequency filters. A methodology is proposed which generates a number of fundamentally new active elem ents with their potential utilization in various areas o f signal processing.

Active Elements for Analog Signal Processing: Classification, Review, and New Proposals

The authors present a new versatile circuit building block called a differential difference current conveyor (DDCC). An IC technique for implementing the DDCC is also presented. The DDCC-based frequency-selective circuits and nonlinear building blocks such as multiplier, squarer and square rooter are developed. Experimental results are given to demonstrate the feasibility of the proposed techniques, and they show that DDCC-based circuits offer a competitive design choice to CCII-based and DDA-based circuits.

/pdf/cmos-differential-difference-current-conveyors-and-their-3dmi0gt50s.pdf

CMOS differential difference current conveyors and their applications

A two-dimensional (2-D) cellular neural network (CNN) array of resistively coupled Chua circuits which can be designed to implement some elementary aspects of spatial recognition, namely, distinguishing open curves from closed ones and locating the shortest path between two locations, is described. In the latter, two situations are analyzed: flat and wrinkled surfaces. The 2-D CNN array of Chua circuits is shown to be capable of finding the shortest path between two points on a wrinkled labyrinth. The performance of this parallel processing approach was examined using computer simulations, although this method can be implemented in real time via VLSI technology. >

Autowaves for image processing on a two-dimensional CNN array of excitable nonlinear circuits: flat and wrinkled labyrinths

This article presents a basic current-mode building block for analog signal processing, namely current controlled current conveyor transconductance amplifier (CCCCTA). Its parasitic resistance at current input port can be controlled by an input bias current. It is very suitable for use in current-mode signal processing, which is becoming more popular than voltage mode. The proposed element is realized in a bipolar technology and the performances are examined through PSPICE simulations, displaying usabilities of the new active element. The CCCCTA performs tuning over a wide current range. The description includes some examples as a current-mode universal biquad filter, voltage-mode universal biquad filter, a grounded inductance simulator, a current-mode multiplier/divider and an oscillator. They occupy only a single CCCCTA.

Current controlled current conveyor transconductance amplifier (CCCCTA): a building block for analog signal processing

In this paper, using a minimum number of passive components, i.e., new grounded and floating inductance simulators, grounded capacitance multipliers, and frequency-dependent negative resistors (FDNRs) based on one/two modified current-feedback operational amplifiers (MCFOAs), are proposed. The type of the simulators depends on the passive element selection used in the structure of the circuit without requiring critical active and passive component-matching conditions and/or cancellation constraints. In order to show the flexibility of the proposed MCFOA, a single-input three-output (SITO) voltage-mode (VM) filter, two three-input single-output (TISO) VM filters, and an SITO current-mode (CM) filter employing a single MCFOA are reported. The layout of the proposed MCFOA is also given. A number of simulations using the SPICE program and some experimental tests are performed to exhibit the performance of the introduced structures.

A Modified CFOA and Its Applications to Simulated Inductors, Capacitance Multipliers, and Analog Filters

Part I Evolution and hardware implementation of Current Conveyors -- The evolution and the history of Current Conveyors -- Hardware implementations of CCs using off-the-shelf ICs -- Integratable Bipolar CC architectures and commercially available IC CCs -- CMOS implementations of Current Conveyors -- Part II The early (First generation) applications of basic CCI and CCII -- Basic analog circuit building blocks using CCs and application of CCs in impedance synthesis -- First, Second and Higher order filter design using Current Conveyors -- Realization of Sinusoidal Oscillators Using CCs -- Nonlinear Applications of CCs.                            .

Current Conveyors: Variants, Applications and Hardware Implementations

New single-element-controlled sinusoidal oscillator (SECO) circuits using only two current-feedback operational amplifiers (CFOAs) and only five passive elements [two/three grounded capacitors (GC) and three/two resistors] are presented, which not only enlarge the previously known class of two-CFOA-GC SECOs but also provide new configurations that possess properties not available in the previously known circuits. The new oscillators are useful from the viewpoint of applications in several instrumentation and measurement situations such as oscillator-based capacitance measurement schemes, realization of very low frequency oscillators, and the design of voltage-controlled oscillators. Experimental results based upon commercially available AD844-type CFOAs are included, which confirm the practical workability of the new oscillator configurations

New CFOA-Based Single-Element-Controlled Sinusoidal Oscillators

New current-mode universal biquad filter

A new universal current-mode biquad filter using current differencing transconductance amplifier (CDTA) is proposed. The proposed configuration can realize the second-order low pass, high pass, band pass, and band reject responses simultaneously. The circuit employs both grounded capacitors (ideal for integrated circuit implementation), and offers low active and passive sensitivities. The workability of the proposed configuration has been verified using SPICE simulation.

Data Ram Bhaskar

Papers

Current Conveyors: Variants, Applications and Hardware Implementations

New CFOA-Based Single-Element-Controlled Sinusoidal Oscillators

New current-mode universal biquad filter

Universal current-mode biquad filter using dual output current differencing transconductance amplifier

Current Feedback Operational Amplifiers and Their Applications