Current-mode Oscillator Research Articles

An Explicit Output Current-mode Quadrature Sinusoidal Oscillator and a Universal Filter Employing Only Grounded Passive Components - a Minimal Realisation

The use of voltage differencing current conveyor as an active device to design a current-mode oscillator along with a universal filter with only grounded passive elements is the main focus of this manuscript. This re-arranging circuit can work as a sinusoidal oscillator as well as a current-mode universal filter, by simple selection of passive switches. Both the circuits employ only two active devices and three grounded passive elements. The designed oscillator provides two distinctive current outputs with a quadrature-phase difference. It also maintains an independent condition of oscillation and frequency of oscillation. Moreover, the basic responses including low pass, high pass, and band pass are easily available from a current-mode universal filter. The low input impedance and high output impedance are amongst the noteworthy features of the current-mode derived filter. Non-ideal, parasitic, and sensitivity analysis of the designed circuits are also incorporated in the manuscript. Cadence PSPICE software simulation results are also included to justify the design idea. Experimental implementation of the described circuit has also been shown by employing special-purpose amplifier integrated circuit, i.e., OPA860.

Implementation of RC Oscillator with High-Q Frequency Selection using CCCII.

This article given a second generation current controlled current conveyor positive (CCCII+), second generation current controlled current conveyor negative (CCCII-), Quadrature oscillator with high-Q frequency choosing network and implementing completely different phase oscillators by employing (CCCII+) positive and (CCCII-) negative, and high band pass filter network, the approach is predicted on the CMOS technology . The root of this concept is, considering a customary voltage mode oscillator which consists of band pass filter with prime quality issue (high-Q) and voltage mode amplifier is transfigure into current mode oscillator by replacing tans-conductance amplifier. Because the loop of the oscillator is has lavish selectivity, the oscillator process less distortion. In addition 3dB bandwidth, oscillating condition, oscillation frequency of the oscillator could linearly, independently and electronically be tuned by adjusting the bias current of the (CCCII±)[1], lastly different simulations have been carried out to verify the linearity between output and input ports, range of frequency operations. These results can justify that the designed circuits are workable.

RC oscillators based on high‐Qfrequency‐selecting network

In this study, a traditional voltage-mode oscillator consisting of a high-Q band-pass filter and a voltage amplifier is transformed into a current-mode oscillator employing a trans-conductance amplifier. Furthermore, a current-mode quadrature oscillator with a high-Q band-pass filter and second generation current-controlled conveyors (CCCIIs) is presented. Since the loop of the oscillator has rich selectivity, the oscillator produces less distortion. Also, the 3 dB bandwidth, oscillation criterion, and oscillation frequency of the oscillator could independently, linearly, and electronically be tuned by the aid of adjusting bias currents of the CCCIIs. Finally, the validity of the designed circuit is verified by means of the computer simulation and the non-ideal analysis is performed to explain the results of the simulation. The results show that the designed circuit is workable.

New current-controlled current-mode sinusoidal quadrature oscillators using CDTAs

This article presents new current-mode oscillator circuits using CDTAs which is designed from block diagram. The proposed circuits consist of three CDTAs and two grounded capacitors. The condition of oscillation can be adjusted electronically/orthogonally from the oscillation frequency by adjusting bias current of the CDTAs. The proposed quadrature oscillators have high output impedance and use only grounded capacitors without any external resistor which is very appropriate for future development into an integrated circuit. The PSPICE simulation and experimental results are corresponding to the theoretical analysis.

Quadrature oscillator using CCCCTAs and grounded capacitors with amplitude controllability

The realisation of two electronically tunable current-mode quadrature oscillators using Current Controlled Current Conveyor Tranconductance Amplifiers (CCCCTAs) and grounded capacitors is presented. The proposed circuits offer the following advantages. The condition of oscillation and the frequency of oscillation can be orthogonally controlled. Availability of electronic control of amplitude of output current is achieved. The oscillators have high outputs impedance which facilitates easy driving an external load without additional current buffers. The proposed circuits are constructed by using two active elements and all grounded capacitors which are attractive for integration and have low active and passive sensitivities. The PSPICE simulation and experimental results are included to show the workability of the proposed circuit.

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

AbstractThe 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.

Transformation of a floating capacitor oscillator to a family of grounded capacitor oscillators

A recently reported two current feedback operational amplifier (CFOA)-based oscillator is converted to a family of 16 current mode oscillators using CCII or ICCII or combination of both. A transformation method based on nodal admittance matrix (NAM) expansion is used to transform the floating capacitor CFOA-based oscillator circuit to a family of 16 grounded capacitor oscillators using CCII or ICCII or combination of both. Two of the new grounded capacitor oscillator circuits have a floating property. Simulation results are included.

Current conveyor based or unity gain cells based two integrator loop oscillators

Four alternative families of oscillators are considered in this paper, three of the families employ CCII or ICCII or combination of both and each family has sixteen oscillator circuit members. The fourth family uses unity gain cells and has four circuit members. Two alternative transformation methods are used in this paper for the generation of oscillators. The first one uses the adjoint circuit theorem to obtain a new family of current mode oscillators from a voltage mode oscillator circuit. The second transformation method uses the nodal admittance matrix (NAM) expansion to generate a grounded passive element oscillator family from an oscillator circuit, which employs a virtually grounded resistor. Although this paper has a tutorial nature it includes two new families of oscillators; one of them provides both current and voltage outputs and the other provides voltage outputs and is based on the use of voltage, current followers and inverters. Simulation results are included to support the analysis.

Generation of three oscillator families using CCII and ICCII

New minimum passive component current mode oscillators are given. Two of the new oscillators have a floating property. Two families of 16 grounded passive component oscillators each are generated from two current conveyor based oscillators. The generation method is based on the combination of both types of current conveyors and inverting current conveyors. Additional oscillators are generated using the adjoint network theorem. Some of the oscillator circuits considered in this paper have the advantage of being easily compensated for the parasitic effects of the current conveyors.

A current mode equalizer for an optical disc front-end

A 1.2 V current-mode 7th-order Bessel low pass filter (LPF) with programmable boosting gain for an optical disc front-end is presented. The wide cut-off frequency tuning is achieved by using current-mode buffers, triode region MOS resistors and varactors. The constant gm biasing and the current-mode oscillator ensure that frequency characteristics are robust to process, voltage and temperature variations. It covers a wide frequency tuning range of 1-140 MHz and speeds of CD 4x - BD 8x, for CD/DVD/BD. It has a low power consumption of 19 mW and a small size of 0.167 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and is fabricated with 0.13 mum CMOS technology.

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

AbstractEmploying 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 &amp; Sons, Ltd.

THEORETICAL AND PRACTICAL ASPECTS OF CURRENT MODE RC OSCILLATORS

In this paper it was made a RC oscillator and its transfer function , and it was made a study of errors which affects maintaining gain of oscillations and frecquency of oscillation. The paper point out the experimental results obtain through RC oscillator implementation with PA 630 current conveyors showing that the current mode oscillators appears to be an interesting approach from the perspective of the simplicity/performance compromise.

Electronically controlled currentmode oscillators using MO-OTAs and grounded capacitors

Electronically controlled currentmode oscillators using MO-OTAs and grounded capacitors

Novel Canonic Current Mode DDCC Based SRCO Synthesized Using a Genetic Algorithm

A survey of the technical literature reveals that synthesis of Current Mode (CM) oscillators using single active building block (ABB) requires an additional identical or complementary current terminal to sense and take out the current output. The topologies of these oscillators are essentially based on the current mode approach. They use a Voltage Controlled Voltage Source (VCVS) and two current terminals to implement the CM oscillator. In the present paper, a novel DDCC (Differential Difference Current Conveyor, introduced in Chiu et al. (IEE Proc., Circuits, Devices, Syst., vol. 143, no. 2, pp. 91–96, 1996)) based canonic CM Single-Resistor Controlled Oscillator (SRCO) is presented, which uses a VCVS and a single current terminal to take out the output. Earlier, authors used DDCCC (Differential Difference Complementary Current conveyor), DVCCC (Differential Voltage Complementary Current Conveyor) to implement CM oscillators and hypothesized the requirement of an additional current terminal for the output. The synthesis of present topology indicates that DDCC is a versatile building block to implement canonic CM SRCOs and doesn't need any additional current terminal. This topology was synthesized using an innovative genetic algorithm. Spice simulations have been included and they verify theoretical results.

CMOS sinusoidal oscillator based on current-controlled current conveyors

A new realisation of a CMOS single resistance current-controlled current mode oscillator using active grounded resistances is described. A prototype has been realised in 0.8 µm CMOS technology from AMS. Measurement results confirm oscillation over 10 MHz, low output distortion and wide tuning range.

Minimum realisation for FTFN-based SRCO

Minimally realised single-resistance-controlled sinusoidal oscillators using one positive four-terminal floating nullor (FTFN+) have been presented. The proposed structure consists of five passive elements, the attractive features being independent control of the oscillation condition and the oscillation frequency, and low passive and active sensitivities. By replacing the FTFN+ with a multiple output FTFN+, current-mode oscillators with high output impedance can be obtained. The feasibility of the proposed circuits is demonstrated by experimental results.

Current mode oscillator with linear period control over a wide range

Recently there has been increasing interest in current mode oscillator structures. The topologies in the literature are focused mainly on the use of a minimum number of grounded passive components, considering the suitability for integration, but none of them allows linear period control which is essential for many applications. The topology presented in this paper allows linear single element control of the period of the output signal over many decades and is suitable for integration.

Synthesis of grounded capacitor and grounded resistor oscillators

Three novel oscillators that employ grounded capacitors and grounded resistors and using the current conveyor as the active building block are given. The proposed oscillators are based on modification of the well known two-integrator loop oscillator. The proposed oscillators have the advantages of independent oscillation control by varying a single grounded resistor as well as independent frequency control through another grounded resistor. A novel current mode oscillator using two-output current conveyors is generated from one of the proposed oscillators. The oscillators reported in this paper are suitable for very large-scale integration, by using MOS grounded resistors. PSpice simulations to confirm the excellent performance of each of the proposed oscillators are included.

High frequency current mode oscillator employing f T integration technique

A low distortion high frequency oscillator is described, which is a development of the recently proposed fT-integrator, in which an amplitude control circuit is embedded inside the integrator. Simulation results suggest that, for the oscillation range 1–2.6 GHz, the total harmonic distortion (THD) of the output current signal is well below 0.5% for the output current level at 50% modulation depth (peak-to-peak). The phase noise of the oscillator is simulated to be –72 dBc/Hz at 1 MHz offset for 1% THD output current.

Novel generation method of current mode Wien-type oscillators using current conveyors

A new approach to the generation of current mode Wien-type oscillators using the current conveyor is introduced. The proposed method is based on replacing the generalized current negative impedance converter in the conventional Wien oscillator by a well-known equivalent circuit realized using the current conveyor. A family of four new current mode oscillators employing grounded capacitors derived from the corresponding classical op amp Wien oscillator family is given. The proposed oscillators have the attractive advantage that the condition of oscillation and the frequency of oscillation can be independently controlled without affecting each other. PSpice simulation results supporting the theoretical analysis are given.