Single-resistance-controlled Oscillators Research Articles

An ingenious methodology of deriving single‐FTFN‐based canonic grounded‐capacitor SRCOs

SummaryIn the past, several new active elements have been employed to realize single‐resistance‐controlled oscillators (SRCO) of which the four‐terminal‐floating‐nullors (FTFN) have attracted considerable attention in the literature. In this paper, an ingenious methodology of deriving single‐FTFN‐based canonic grounded‐capacitor (GC) SRCOs has been presented. It is shown that such oscillators can be systematically evolved from a class of earlier known op‐amp‐based SRCOs through the application of two theorems pertaining to RC‐nullor oscillators published earlier. The presented methodology not only yields all the previously known (four) single‐FTFN‐based canonic GC SRCOs but also reveals a number of (12) new circuits, which have not been known in the open literature earlier. The viability of the evolved oscillator circuits has been confirmed through SPICE simulations, and some simulation results have been given.

On the realisation of canonic single‐resistance‐controlled oscillators using third generation current conveyors

This study presents findings of a search on canonic single-resistance-controlled oscillators (SRCOs) using third generation current conveyors (CCIIIs). From seven identified canonic SRCOs, five are completely new. All seven canonic SRCOs use two CCIIIs, two grounded capacitors and three resistors. The condition of oscillation and frequency of oscillations are decoupled and simple. The workability of the presented oscillator configurations have been confirmed by PSPICE simulation and hardware experiments.

A State Variable Method for the Realization of Universal Current-Mode Biquads

A state variable method of converting single-resistance-controlled- oscillators (SRCO), into universal current-mode biquad (offering realizations of all the five standard filter functions namely, low pass, band pass, high pass, notch and all pass) has been highlighted. The workability of the exemplary implementation of the derived current-mode universal biquad has been demonstrated by PSPICE simulation results based upon 0.35 μ m technology. It is expected that the proposed method can be applied to other SRCOs to generate other multifunction filter structures.

Realisations of single-resistance-controlled quadrature oscillators using a generalised current follower transconductance amplifier and a unity-gain voltage-follower

This article presents realisations of single-resistance-controlled-oscillators (SRCOs) using the recently proposed modern active building block (ABB), namely the generalised current follower transconductance amplifier (GCFTA) and unity-gain voltage-follower (UGVF). The SRCO is made using reduced number of components: one GCFTA and one UGVF as the ABBs, two resistors and two grounded capacitors. The circuit offers the advantage of non-interactive control of condition of oscillation and frequency of oscillation and enjoys low active and passive sensitivities. The circuit is also capable of providing two quadrature voltage outputs. PSPICE simulations have been carried out using the bipolar implementation of the circuits. The simulation results validate the theoretical analysis.

Additional Realizations of Single-element-controlled Oscillators Using Single ICCII

This paper presents additional realizations of single-element-controlled oscillators (SECOs) using a single negative-type inverting second-generation current conveyor (ICCII-). The circuits have been derived from a single ICCII- based topology previously proposed by Toker et al. Both single-resistance-controlled oscillators (SRCOs) and SECOs have been obtained. The circuits use one ICCII- and five/six external passive components, hence reduced number of components are employed. The circuits also provide explicit-current-output (ECO) and enjoy low active and passive sensitivities. PSPICE experimental results have been included to verify the theoretical results.

Designing SRCOs by combining SPICE and Verilog-A

The design of single-resistance-controlled oscillators (SRCOs) is presented by using current followers (CF) and voltage followers (VF). First, the design of the followers is described by using SPICE and standard CMOS technology of 0.35 µm. Second, a SRCO is simulated in SPICE by using the designed CF and VF. Third, the SRCO is simulated in Verilog-A by using ideal and real behavioural models for the followers. Finally, the good agreement on the simulation results leads us to conclude on the usefulness to combine SPICE and Verilog-A to enhance analogue integrated circuit design.

Two new canonic single-CFOA oscillators with single resistor controls

Although a number of single current feedback op-amps (CFOA)-based single-resistance-controlled oscillators (SRCO) have appeared in earlier literature, only six of them are canonic (i.e., requiring only two capacitors and only three resistors). The object of this brief is to add to this list two new canonic single-CFOA-based SRCO configurations. An evaluation of these two new circuits has been carried out and their workability of has been confirmed by experimental results based upon AD844 CFOAs.

Grounded-capacitor SRCOs using a single differential difference complementary current feedback amplifier

The usefulness of a new active building block, the ‘differential difference complementary current feedback amplifier' (DDCCFA) in realising single resistance controlled oscillators (SRCO) employing grounded capacitors has been demonstrated and using a state-variable methodology, a number of new single DDCCFA-based SRCOs have been derived. It is shown that the new SRCOs possess features, all of which are not available simultaneously in any single active building block-based SRCOs known earlier. The workability of the proposed circuits has been varified by SPICE simulations using a DDCCFA implementable in 0.35 micron CMOS technology.

On the realization of oscillators using state equations

In this work, an extension to the oscillator synthesis method using the state variable technique is presented. It is shown that using suitable block diagrams, which represent the state equations, systematic circuit realizations can be performed. The most critical steps of the presented method are the selection of the suitable characteristic equation and thederivation of the corresponding sub-circuits. The selection criteria of thecharacteristic equations for the realization of single resistance controlled oscillators (SRCOs) are also given. By using the extended state variable synthesis method, SRCOs employing a single current feedback amplifier (CFA)are obtained. Furthermore, a new active element, namely the differentialvoltage current feedback amplifier (DVCFA) is proposed for the realization of oscillators employing only grounded capacitors and new SRCOs employing thisactive element are presented. SPICE simulations and experimental results confirm the operation of the presented oscillators.

Novel SRCOs using first generation current conveyor

This paper presents two new single-resistance-controlled-oscillators (SRCOs), that employ a single first-generation current conveyor (CC) along with one/two voltage buffer(s) and a minimum of (five) passive components. Apart from providing noninteractive controls for both frequency of oscillation and condition of oscillation, a novel feature of these circuits is that they provide voltage-mode as well as currentmode outputs explicitly from the same structures, which is not available in any of the single-CC-based SRCOs published previously.

Grounded-capacitor current-mode SRCO: Novel application of DVCCC

An examination of the technical literature on grounded-capacitor (GC) single resistance controlled oscillators (SRCO) has revealed that no GC-SRCO has so far been published which uses only a single active building block (ABB), only two GCs and provides a current mode (CM) output with simple design equations and unconstrained tuning law. The authors not only introduce such a circuit which uses a single ABB called a ‘differential voltage complementary current conveyor’ (DVCCC) but also indicate that a DVCCC is a versatile building block for realising SRCOs. The feasibility of the proposed formulation has been verified in PSPICE using a CMOS implementation of the DVCCC.

State variable synthesis of single-resistance-controlled grounded capacitor oscillators using only two CFOAs: additional new realisations

The authors report eight new ‘two-CFOA–two-grounded-capacitor–three-resistor’ single-resistance-controlled oscillators (SRCO) and the results of experimental investigations of the fourteen SRCOs of this class (including six introduced in an earlier communication).

Synthesis of single-resistance-controlled oscillators using CFOAs: simple state-variable approach

A simple state-variable synthesis approach has been presented which makes it possible to evolve current feedback op-amp (CFOA)-based single-resistance-controlled oscillators (SRCO) systematically. Synthesised SRCOs possess several novel features and their workability has been confirmed experimentally as well as through SPICE simulations using commercially available AD844 CFOAs.

Identification and design of single amplifier single resistance controlled oscillators

From a unified representation of single amplifier active- RC networks, a set of new single resistance controlled oscillator (SRCO) circuits are identified. These are canonic with respect to the number of capacitors and have minimal component count. A detailed analysis of these circuits has been carried out and the experimental results are given.