The electronically tunable quadrature oscillator using a single multiple-output current controlled current differencing transconductance amplifier (MO-CCCDTA) and grounded passive components is presented. The proposed configuration uses a single MO-CCCDTA, two grounded capacitors and one grounded resistor. Two high-output impedance quadrature current signals and two quadrature voltage signals with 90° phase difference. The oscillation condition and oscillation frequency of the proposed quadrature oscillator are independently controllable. The use of only grounded passive components makes the proposed circuit ideal for integrated circuit implementation.

At present, there is a growing interest in designing analogue current-mode signal-processing circuits. Various new current-mode active building blocks have received considerable attentions owing to their larger dynamic range, greater linearity, wider bandwidth, and low power consumption with respect to operational amplifier-based circuits [

In 2003, a new current-mode active element that is called current differencing transconductance amplifier (CDTA) was introduced [

In this paper, the author also proposes another simple electronically controllable grounded capacitor quadrature oscillator using a single MO-CCCDTA. The proposed circuit has all of the advantages by Prasad et al. [

MO-CCCDTA is relatively new active element [

MO-CCCDTA symbol [

The proposed current-mode and voltage-mode quadrature oscillator.

From (

The relationships between output voltages

Clearly, the current-mode and voltage-mode quadrature signals can be simultaneously obtained from Figure

Taking the nonidealities of the MO-CCCDTA into account, the relationship of the terminal voltages and currents can be rewritten as

The active and passive sensitivities remain less than unity and hence the circuit exhibits a satisfactory sensitivity performance.

A study is next carried out on the effects of various parasitics of the MO-CCCDTA used in the proposed circuit. A practical MO-CCCDTA device can be modeled as ideal MO-CCCDTA with finite parasitic resistances and capacitances. Figure

Nonideal equivalent circuit model of the MO-CCCDTA.

In order to verify the theoretical analysis, the proposed oscillator has been simulated using HSPICE program by using TSMC 0.18

CMOS implementation of MO-CCCDTA [

Transient amplitudes of the waveforms of

Transient amplitudes of the waveforms of

Simulated quadrature voltage output waves of

Simulated quadrature current output waves of

The simulated frequency spectrum of

The simulated frequency spectrum of

Variation of transconductance with bias current

Oscillation frequency against the bias current

Phase error as a function of oscillation frequency (blue: phase error versus

Total harmonic distortion (THD) as a function of oscillation frequency (blue:

In this paper, a new quadrature oscillator circuit using a single MO-CCCDTA, two grounded capacitors, and one grounded resistor is presented. The oscillation condition and oscillation frequency of the proposed quadrature oscillator have the advantage of being independently controllable. Two high-output impedance sinusoid currents with a 90° phase difference are available in the proposed configuration. The use of all grounded passive elements makes the proposed circuit ideal for integrated circuit implementation. Both current-mode and voltage-mode quadrature signals can be simultaneously obtained in the proposed circuit. HSPICE simulation results have confirmed the workability of the circuit.

The author declares that there is no conflict of interests regarding the publication of this paper.

The author is thankful to the anonymous reviewers for their suggestions to improve the paper. The author is also grateful to Professor Soliman A. Mahmoud, Editor, for recommending this paper.

_{0}-Q control based on new digitally programmable CMOS CCII