Harmonic oscillators realized using current amplifiers and grounded capacitors

New configurations of harmonic oscillators, realized using current amplifier blocks and only grounded capacitors, are introduced in this article. The proposed configurations are based on a grounded inductor simulator scheme and on a loop constructed from first‐order sections, respectively. Comparison with the already published topologies shows that the new configurations have attractive characteristics concerning their implementation in integrated form. Copyright © 2006 John Wiley & Sons, Ltd.     

Current mode filters using two output inverting CCII

Current mode Tow Thomas filter using two‐output inverting second‐generation current conveyor is given, the circuit has low input impedance, employs two grounded capacitors and three grounded resistors and has independent control on Q. A universal current mode filter capable of realizing the five filter functions is also given. Both circuits have low sensitivities to all circuit components. Spice simulation results are included. Copyright © 2007 John Wiley & Sons, Ltd.     

Voltage mode and current mode Tow Thomas bi‐quadratic filters using inverting CCII

A voltage mode Tow Thomas bi‐quadratic filter using the inverting second‐generation current conveyor (ICCII) is given. The filter has high input impedance, employs two grounded capacitors, and has independent control on Q, independent control on the band‐pass and low‐pass response gain. Three alternative current mode filters are generated from the voltage mode circuit. The three circuits have zero input impedance, employ grounded capacitors and have independent control on Q. Two of the circuits have also all resistors grounded and the other uses only ICCII?and has only one floating resistor. Copyright © 2007 John Wiley & Sons, Ltd.     

Structural generation of two integrator loop filters using CDTAs and grounded capacitors

A versatile family of two integrator loop filter structures using current differencing transconductance amplifiers (CDTAs) and grounded capacitors is generated. The basic filter building blocks consist of current proportional blocks, current lossless integrators and a current lossy integrator based on the use of CDTAs as the major active components. It is demonstrated that the derived filter structures can realize a general class of second‐order current transfer functions. Since the resulting structures contain only CDTAs and grounded capacitors, they are general and very appropriate for integration, cascading and electronic tuning. The influences of the CDTA non‐idealities are also discussed. The functionality of the resulting filters has been verified by simulation results. Copyright © 2009 John Wiley & Sons, Ltd.     

Electronically controlled multiphase sinusoidal oscillators using current amplifiers

A novel current‐mode multiphase oscillator topology is introduced in this letter. This is realized by employing current amplifiers and only grounded capacitors. Attractive characteristics offered by the new topology are the electronic adjustment of the oscillation frequency, the absence of passive resistors, and the requirement of only grounded capacitors. Comparison with the corresponding already published current follower based structure shows that the proposed topology has better performance in terms of the number of required active elements, the employment of passive resistors, and the ability for electronic adjustment of the oscillation frequency. Copyright © 2008 John Wiley & Sons, Ltd.     

Realization of tunable RC-active oscillators using grounded capacitors and voltage amplifiers

A systematic procedure is given to generate a set of tunable RC oscillators, each using two finite gain voltage controlled voltage sources, three resistors and two grounded capacitors. These realizations are shown to be minimal with respect to passive and active elements under the constraint that (one end of) all the capacitors remain grounded. The set consists of four oscillators and is shown to be complete, that is, no additional oscillator circuit can be generated under the given assumptions. A simple approach is then introduced for testing the structures for latch up behaviour. This approach also suggests a way of redesigning the oscillator circuits to render them free of latch up problems, if they exist. Experimental results are found to be in good agreement with the theory.     

CMOS digitally programmable quadrature oscillators

CMOS digitally programmable quadrature oscillators based on digitally controlled current followers and voltage followers are proposed. The proposed designs provide the advantage of programmability similar to the operational transconductance amplifier‐based oscillators while offering improved linearity. In mixed analog/digital systems, the digital tuning feature allows direct interfacing with the digital signal processing part. Novel realizations that provide both voltage‐mode and current‐mode quadrature sinusoidal signals are presented. Employing only grounded capacitors the designs achieve independent control of the frequency and condition of oscillation that can be tuned digitally. Experimental results obtained from a 0.35 µm CMOS chip fabricated using standard CMOS process are given. Copyright © 2008 John Wiley & Sons, Ltd.     

Sinusoidal oscillators with explicit current output employing current‐feedback op‐amps

Employing a state‐variable synthesis, a number of new current‐mode oscillators with explicit current output have been derived, which can be practically implemented from commercially available current‐feedback op‐amps (CFOA). The workability of the proposed structures has been confirmed by experimental results using AD844‐type CFOAs and some sample results have been presented. Copyright © 2008 John Wiley & Sons, Ltd.     

Switching‐mode counterparts of the Rayleigh and Van‐der‐Pol oscillators

The present work deals with two fundamental oscillator models. One of them can be regarded as a switching‐mode counterpart of the Rayleigh oscillator, while the other can be regarded as a switching‐mode counterpart of the Van‐der‐Pol oscillator. The models are investigated by several means. Their structure is discussed by treating their circuit models. It is also shown that the related differential equations can be solved analytically and explicit forms of exact solutions are attained by employing recursive algebraic processes. The latter solutions are successfully compared to comprehensive direct simulations based on the original differential equations. Furthermore, the exhibited solutions of the switching‐mode counterparts for small and moderate values of ϵ are shown to be closely similar to the solutions of their parent oscillators. Possible applications of the present oscillatory models are discussed. It is argued that the models can favourably serve for simply representing biological and other systems that rely on oscillatory processes. Copyright © 2000 John Wiley & Sons, Ltd.     

High output impedance CMQOs using DVCCs and grounded components

In this paper a new circuit topology for realizing second‐order current‐mode quadrature oscillator is proposed. Three additional circuits are further derived from it, thus resulting in four distinct circuits. Each circuit employs three differential voltage current conveyors and all grounded passive components, ideal for IC implementation. All the circuits possess high output impedance. The circuits exhibit non‐interactive frequency control and low THD. The effects of non‐idealities are also analyzed. PSPICE simulations using 0.5 µCMOS parameters confirm the validity and practical utility of the proposed circuits. Copyright © 2010 John Wiley & Sons, Ltd.     

Realization of arbitrary current transfer functions based on commercially available CCII + s

In this paper, a new topology for realizing arbitrary n^th‐order current transfer function (TF), consisting of only plus‐type second‐generation current conveyors (CCII+s), is suggested. The proposed TF simulator employs only grounded capacitors and is free from the passive element matching requirements. The developed TF simulator can be constructed directly with commercially available active components such as AD844s. It has low‐input and high‐output impedances, a feature which makes it fully cascadable with other current‐mode topologies. Moreover, the proposed simulator can provide gain at its outputs. Simulation and experimental test results for various filter examples are included to confirm the claimed theory. Copyright © 2012 John Wiley & Sons, Ltd.     

Current-mode multiple-loop feedback filters using dual-output OTAs and grounded capacitors

A systematic method is presented for the generation, analysis and synthesis of current-mode continuous-time multiple-integrator-loop all-pole filters using dual-output operational transconductance amplifiers and grounded capacitors (DO-OTA-GC). The general theory based on a multiple-loop feedback model is formulated. A number of architectures including canonical realizations are developed, with particular emphasis on high-order configurations. A sensitivity analysis method is also given and parasitic effects on the structures are discussed. The general formulations are verified by direct analysis of the generated individual circuits. Design examples are also presented. © 1997 by John Wiley & Sons Ltd.     

A numerical model for the oscillation frequency,the amplitude and the phase‐noise of MOS‐current‐mode‐logic ring oscillators

This paper presents a new model for the frequency of oscillation, the oscillation amplitude and the phase‐noise of ring oscillators consisting of MOS‐current‐mode‐logic delay cells. The numerical model has been validated through circuit simulations of oscillators designed with a typical 130 nm CMOS technology. A design flow based on the proposed model and on circuit simulations is presented and applied to cells with active loads. The choice of the cell parameters that minimize phase‐noise and power consumption is addressed. Copyright © 2009 John Wiley & Sons, Ltd.     

Alleviation of a transient stability crisis using shunt braking resistors and series capacitors

As a result of a severe disturbance, a bulk electric power system may be perturbed into an emergency state condition, whereby transient stability is not maintained and machine synchronous operation is lost. A generic methodology is presented that uses physical control means to alleviate such a transient stability crisis. Series braking capacitors and shunt braking resistors are the primary control means for such an event because of their speed of operation. The paper presents a simple control model formulated in an observation decoupled Thévenin equilibrium frame as a control space. This approach requires only locally available measurements. The minimum angle optimal aiming strategy is used to decide on necessary control action, which is then implementable through direct and inverse influence mappings presented for the two control means considered. Experimental results are also included to indicate the practical usefulness of these techniques.     

Current/voltage mode full-wave rectifier based on a single CCCII

A novel full-wave rectifier (or inverting full-wave rectifier) based on a single second-generation current controlled conveyor (CCCII) having no external passive components and diodes, conducive to IC implementation, is proposed in this paper. The circuits are capable of precisely processing the input signals of up to 30 MHz frequency, while in the situation when the circuits are operating in a voltage mode (VM), the allowed range of possible changes in the input voltage signal is ±500 mV compared with ±1 mA in the current mode (CM). In order to more fully perceive the performance of the proposed full-wave rectifier, the influence of nonidealities and parasitic impedances effects on its work was analyzed. The simulation results using 0.35-μm parameters confirm the feasibility of the proposed solutions.     

电流模电路及其应用

文中主要阐述电源模分析技术。通过对各个电流模单元电路及其原理的介绍，描述了这种新的分析方法，使读者可以应用跨导线性电路，电流镜，电流传输器，开关电流电路等单元电路分析常用电子电路。     

Pathological representation of the two‐output CCII and ICCII family and application

The pathological mirror and nullor representation of the two‐output current conveyor family is given. New pathological mirror and nullor representations of the two‐output current conveyor family are given and compared with the corresponding nullator norator resistors' realizations. Simplified representations of the two‐output current conveyors based on using two single‐output current conveyors are given. Two examples are given, the first example demonstrates the importance of the pathological representation in the generation of a family of 16 oscillators from a two‐output current conveyor‐based current mode oscillator. A second example of a current mode low‐pass filter using two single‐output inverting current conveyors is considered. Its simplified modeling using a single balanced output inverting current conveyor is compared with the original current mode filter and the simulation results are given. Copyright © 2010 John Wiley & Sons, Ltd.     

Generation and classification of CCII and ICCII based negative impedance converter circuits using NAM expansion

A new simplified generation method of negative impedance converter circuits (NIC) is introduced. The generation method is based on nodal admittance matrix expansion starting from the input admittance of the NIC circuit terminated by a load rather than treating the NIC as a two‐port network element. The four pathological elements, namely nullator, norator, voltage mirror and current mirror, are used in the generation procedure. Two classes of the NIC pathological circuits are defined; each class includes two types. Eight pathological NIC circuits are generated for each class. Two alternative current conveyor and inverting current conveyor‐based realizations for each pathological circuit based on alternative pairing of the pathological elements are defined resulting in a total of 16 NIC circuit for each class and a total of 32 NIC circuits. A new NIC‐based circuits realizing floating negative impedances are also introduced. Copyright © 2010 John Wiley & Sons, Ltd.