An electronically tunable current-mode quadrature oscillator using PCAs

Abstract

The paper presents a new realization of active RC sinusoidal oscillator with electronically tunable condition and frequency of oscillation. As compared to the class of three resistors, two capacitors (3R-2C) based canonic oscillators, the proposed circuit here uses only two resistors and two capacitors as the passive components and still provides non-interactive tuning laws for the condition of oscillation (CO) and the frequency of oscillation (FO). The proposed circuit employs new bipolar programmable current amplifier (PCA) as the active building block and is capable of simultaneously providing two explicit quadrature current outputs. SPICE simulation results have been included to verify the workability of the circuit as an oscillator and the tuning range of the FO.

New Double Current Controlled CFA (DCC–CFA) Based Voltage–Mode Oscillator with Independent Electronic Control of Oscillation Condition and Frequency

“…In [1], the review of basic, modified, and novel active elements is also given. In the last years in the literature interesting applications of components mentioned in [1], such as operational transconductance amplifier (OTA) [2,3], current controlled second-generation current conveyor (CCCII) [4,5], dual-X second-generation current conveyor (DXCCII) [6,7], fully-differential secondgeneration current conveyer (FDCCII) [8,9], current feedback amplifier (CFA) [10], current controlled CFA (CC-CFA) [11], modified current feedback operational amplifier (MCFOA) [12], current differencing buffered amplifier (CDBA) [13,14], current differencing transconductance amplifier (CDTA) [15,16], current follower transconductance amplifier (CFTA) [17,18], programmable current amplifiers [19,20], adjustable current followers [21], etc, have been published. Many of these components offer features for electronic control and great frequency response.…”

Quadrature oscillators using two CFOAs and four passive components

“…Also, the quadrature output voltages cannot be obtained from [4,5,6,7]. As a result, a number of CFOA-based circuits have been proposed [3,9,10,11,12]. The structure [3] uses two CFOAs, two/three grounded capacitors and three/ two resistors.…”

“…The structures [10,11,12] employ two CFOAs, two capacitors and three resistors. Although both proposed circuits use the same numbers of CFOA active components with respect to the previous voltage-mode quadrature oscillators in [3,9,10,11,12], two new oscillator circuits employ minimum number of passive elements, namely two resistors and two grounded capacitors. Both proposed circuits simultaneously provide two voltage quadrature signals with 90°phase difference, and still enjoys orthogonal frequency and oscillation control.…”

“…In the last two decades on the realization of voltage-mode oscillators, an application of current-feedback operational amplifier (CFOA) [3,4,5,6,7,8,9,10,11,12], double current controlled current feedback amplifier (DCC-CFA) [13], currentcontrolled current feedback amplifier (CC-CFA) [14], differential voltage current conveyor transconductance amplifier (DVCCTA) [15], differential-input buffered and transconductance amplifier (DBTA) [16], and second-generation conveyor (CCII) [17] have received considerable attention. Moreover, the four terminal CFOA, particularly the commercial available integrated circuit (IC) type AD844 providing an accessible compensation pin, has received prominent attention [3,4,5,6,7,8,9,10,11,12]. Although a number of single CFOA-based oscillators have been proposed in the literature [4,5,6,7], none of them employ both grounded capacitors.…”

First–Order Transfer Sections with Reconnection–Less Electronically Reconfigurable High–Pass, All–Pass and Direct Transfer Character

“…The second group deals with controllable intrinsic resistance (R x ) of the current input terminal (mainly in current-mode active elements) [3]. Control of current gain (B ) [4] becomes very popular in recent years mainly [5][6][7][8][9][10][11]. Utilization of the adjustable voltage gain (A) is also very useful in many cases, but complexity of active elements is worse [12] than basic structures utilizing g m or R x control [2,3].…”