New FTFN-based grounded-capacitor SRCO with explicit current-mode output and reduced number of resistors

A new current-mode single-resistance-controlled-oscillator (SRCO) using two four-terminal-floating-nullors (FTFNs) is presented. The proposed SRCO provides the following advantageous features, not available simultaneously in any of the FTFN-based grounded-capacitor (GC) SRCOs known earlier so far: (i) use of two GCs which are attractive for IC implementation as well as eliminating/accommodating parasitic capacitances, (ii) very good frequency stability, (iii) low active and passive sensitivities, (iv) independent single grounded resistor control of oscillation frequency (as well as availability of such a control through a resistor ratio), (v) ready availability of explicit current-mode output, and above all, (vi) employment of a reduced number (only four) of resistors, in contrast to earlier two-FTFN-GC SRCOs requiring six resistors. Experimental results are included which confirm the practicability of the proposed circuit.     

Current conveyor-based voltage-mode two-phase and four-phase quadrature oscillators

A voltage mode two-phase quadrature oscillator using plus-type second generation current conveyors [CCIIs(+)] is realized by using a simple technique. The basic building block for this technique is a voltage mode non-inverting band-pass filter. The two-phase quadrature oscillator is then transformed into a four-phase quadrature oscillator by replacing the two CCIIs(+) by two dual output, current conveyors [DO-CCIIs]. The proposed circuits enjoy attractive features such as use of grounded passive components, independent frequency control, outputs of almost equal magnitude and low sensitivity figures. Both the oscillator circuits are designed and verified using PSPICE simulation.     

Multiphase sinusoidal oscillators using second generation current conveyors

A voltage-mode Multiphase Sinusoidal Oscillator realized using Second Generation Current Conveyors and only grounded passive elements is introduced in this paper. The proposed topology is suitable for realizing oscillators with both odd and even number of phases without modifying the core of the topology. Only non-inverting Current Conveyors are required for the construction of the oscillator's topology and this is a benefit from the discrete component implementation point of view. The behavior of the proposed topology has been evaluated, through experimental results, in the cases of three and six-phase oscillators.     

Simulation of a mutually coupled circuit using plus-type CCIIs

A new CCII-based circuit for the simulation of mutually coupled circuits is presented. The circuit uses six commercially available plus-type second-generation current conveyors (CCII+s), six resistors and two grounded capacitors. The primary self-inductance, the secondary self-inductance and the mutual inductance can be independently controlled using three different resistors. SPICE simulation results are included.     

Improved grounded-capacitor SRCO using only a single PFTFN

A new circuit configuration for the realization of a single-resistance-controlled Sinusoidal oscillator is presented which uses only one positive four terminal floating nullor (PFTFN) along with two grounded capacitors and five resistors and offers independent control of the frequency of oscillation as well as the condition of oscillation through separate resistors. Experimental results showing the workability of the proposed circuit have been given.     

Fully uncoupled independent control of frequency and condition of oscillation: A caution

Over the years researchers have developed and reported a large number of sinusoidal oscillator circuits and classified them as enjoying fully uncoupled independent control of frequency and condition of oscillation. This classification is based on obtaining the frequency and the condition of oscillation using the Barkhausen criterion. This paper serves as a caution as it appears that this classification is incorrect. Experimental results obtained from recently published circuits; that support this caution, are included.     

Explaining and eliminating latchup in a classical Wien oscillator via nonlinear design

A classical Wien-type sinusoidal oscillator is analyzed to explain the origin of its latchup behavior. Only when a correct nonlinear model of the oscillator is derived and the stability of all equilibrium points associated with each region of operation of the fundamentally nonlinear amplifier characteristics is studied can this phenomena be predicted. It is further shown how latchup can be eliminated. Ahmed S. Elwakil was born in Cairo, Egypt. He received his B.Sc. and M.Sc. degrees from Cairo University and his Ph.D. from the National University of Ireland, all in Electrical and Electronic Engineering. His main research interests are in the area of analog electronic circuit design with particular emphasis on nonlinear circuit analysis and design techniques, nonlinear dynamics and chaos theory. He is author and co-author of more than 70 publications in these areas. Dr. Elwakil is a senior member of IEEE, a member of the IEEE technical committee on nonlinear circuits and systems, a member of IEE, an associate member at the centre for chaos control at the City University of Hong Kong and an associate member at the International centre for Theoretical Physics. He has held several academic visiting positions and has acted as an instructor for two courses on VLSI organized by the United Nations University. He has served as a scientific committee member for many conferences and as a reviewer for numerous journals and conferences. Dr. Elwakil received the Government of Egypt first class medal for achievement in engineering sciences in 2003.     

A Grounded-Resistor Current Conveyor-Based Active-R Multiphase Sinusoidal Oscillator

A multiphase active-R sinusoidal oscillator circuit is presented.The oscillator can produce M signals (M being even or odd) equally spaced inphase. The circuit has low component count, uses grounded resistors andenjoys low active and passive sensitivities. The feasibility of convertingthe circuit into a voltage controlled multiphase oscillator is studied.Simulation results are included.     

Current and transimpedance mode instrumentation amplifier using a single new active component named CDTRA

In this study, both current and transimpedance mode instrumentation amplification operations are met through a new active building block proposal, namely Current DifferencingTransresistance Amplifier block, CDTRA. In order to regard CDTRA as an instrumentation amplifier (IA), two grounded passive resistors are needed. Passive resistors together with electronically tunable transresistance parameter of active block, r_m, set versatility over gain tunability for instrumentation amplifier. Proposed active block is current input, current/voltage output design. It has low impedance input, high impedance for current output, and low impedance for voltage output respectively. Since this particular IA is based on CDTRA, then it inherits these electrical characteristics fully. Numerous SPICE simulations are performed through the paper to verify validity of the study. TSMC 0.18 µm CMOS technology parameters are utilized through simulations. Experimental work is performed for the proposed IA circuit.     

Three port gyrator circuits using transconductance amplifiers or generalized conveyors

The three port gyrator was introduced and defined in [1] in two alternative forms of the admittance matrix (Y). Four alternative realizations of the three port gyrator using three transconductance amplifiers (TA) are given, three of them are new. Sixteen alternative three port gyrator circuits using four current conveyors (CCII) or four inverting current conveyors (ICCII) or a combination of both of them and four grounded resistors are given. Eight alternative three port gyrator circuits using two CCII or two ICCII or a combination of both of them, balanced output current conveyors (BOCCII) and three grounded resistors are also introduced. Eight alternative three port gyrator circuits using two CCII or two ICCII or a combination of both of them, differential voltage current conveyors (DVCC) and three grounded resistors are also introduced. Finally four equivalent three port gyrator circuits using a combination of DVCC and BOCCII and two grounded resistors are also introduced, three of them are new.     

Universal voltage-mode filter using only plus-type DDCCs

Despite the extensive literature on current conveyor-based voltage-mode universal biquads with single input and multiple outputs, no filter circuit has been reported to simultaneously achieve all of the advantageous features: (i) employment of only two differential difference current conveyor (DDCC), (ii) employment only two grounded capacitors, (iii) employment only three resistors, (iv) simultaneously realize voltage-mode low-pass, band-pass, high-pass, notch and all-pass filter signals from the five output terminals, respectively, (v) orthogonal control of ω _o and Q, (vi) low input impedance and can be cascadable (vii) no need to employ inverting type input signals, and (viii) no need to impose component choice except realizing the all-pass filter signal.     

Insensitive high-output impedance minimum configuration SITO-type current-mode biquad using dual-output current conveyors and grounded passive components

This paper presents a high-output impedance current mode single-input and three-outputs (SITO)-type multifunction filter which employs three dual-output current conveyors to simultaneously realize low-pass, high-pass and band-pass responses. The proposed circuit uses grounded-virtually grounded passive components (which makes the circuit ideal for integration and tuning). Moreover, it has low active and passive component sensitivities and does not require critical matching conditions and cancellation constraints.     

First-order allpass filter and sinusoidal oscillators using DDCCs

A voltage-mode first-order allpass filter using one differential difference current conveyor (DDCC), one grounded capacitor and one floating resistor is presented. No passive component matching constraints are required. Because the output impedance of the proposed allpass filter is low, the output terminal can be directly connected to the next stage. Using the proposed first-order allpass filter as a basic building block, a new quadrature oscillator and even-phase sinusoidal oscillators can be obtained. The simulation results confirm the theoretical analysis.     

A new approach for the realization of voltage-mode second-order universal filters using current conveyors

In this work two different types of topologies are derived for realization any second-order filter characteristic by choosing properly, the admittances of passive elements. These topologies use two second-generation current conveyors (CCIIs). One of the topologies involves different types of CCIIs whereas the other uses the same type of CCIIs together with a unity gain voltage buffer. The buffer used provides not only low output impedance but also facilitates cascading of the filter circuits thus obtained. It is possible to derive many different filters realizing any second-order transfer function by the use of the proposed topologies. Moreover, the produced filters have low-sensitivity performance and permit orthogonal controlling of both the quality factor and the natural angular frequency.     

Wide-band resistorless all-pass sections with single element tuning

This paper presents three first order resistorless all-pass filters using combinations of current controlled current conveyors (CCCII) and a unity gain buffer. All circuits feature single element tuning, low sensitivities, and low output impedances, therefore they are suitable for cascading. Circuit simulation results are found in good agreement with theoretical analysis.     

Performance optimization of CMOS second generation current conveyors using a multi-swarm algorithm

This paper proposes an enhanced variant of the particle swarm optimization technique PSO-2S, and its application to analogue circuit performance optimization. For comparison reasons, we focus on performance optimization of a second generation CMOS current conveyor, for different bias current values. It is worth noting that the approach can be easily adapted to deal with other types of circuits. The paper shows that PSO-2S achieves better results than three other well-known optimization techniques, namely bacterial foraging optimization technique (BFO), PSO and differential evolution (DE).     

Current-Mode Universal Filters Using Current Conveyors: Classification and Review

Several current-mode universal filters are reviewed. The filters are classified in two classes. The class I filters have floating passive elements, whereas class II filters have all resistors and capacitors grounded. Each class of filters includes two subclasses based on the filter’s capability to have independent control of the filter quality factor or not. The effects of nonideal second generation current conveyors are briefly discussed. Spice simulations using BSIM3 version 3.1 parameters, feature size 0.5 μm from MOSIS, are given, and a detailed comparison table is included.     

The inverting second generation current conveyors as universal building blocks

The inverting second generation current conveyor ICCII includes two types. This paper concentrates on the two new types of the inverting current conveyor namely ICCII+ and ICCII-. Although it may seem that there is only minor difference between the two types, there is a significant difference as will be evident from some applications considered in this paper. Both the ICCII+ and the ICCII- are universal building blocks as will be demonstrated in this paper.     

High output impedance current-mode universal biquadratic filters with five inputs using multi-output CCIIs

Three current-mode universal biquadratic filters each with five input terminals and one output terminal are presented. The first proposed circuit uses three multi-output second-generation current conveyors, two grounded capacitors and three resistors. This circuit offers the following advantageous features: orthogonal controllability of resonance angular frequency and quality factor, high output impedance, the versatility to synthesize all standard filter types without component matching condition and using grounded capacitors. The second proposed circuit uses three multi-output second-generation current conveyors, two grounded capacitors and two resistors. This circuit offers the following advantageous features: using minimum passive components, high output impedance, the versatility to synthesize all standard filter types without component matching condition and using grounded capacitors. The third proposed circuit uses three multi-output second-generation current conveyors, two grounded capacitors and three grounded resistors. This circuit offers the following advantageous features: the versatility to synthesize all standard filter types, high output impedance and using only grounded passive components. Each of the proposed circuits can get five kinds of filter functions by using only one current input signal.     

High-precision current conveyor implementation employing a current-steering output stage

An improved current conveyor circuit topology based around the use of a current-steering output stage, rather than the more usual current mirrors, is described in this paper. The primary benefit of this approach is a significantly enhanced current transfer linearity through reduced reliance on output-device matching requirements. Outline performance details are given for a discrete version of the circuit and a prototype IC fabricated using this technique.