Electronically Controllable Fully-Uncoupled Explicit Current-Mode Quadrature Oscillator Using VDTAs and Grounded Capacitors

Abstract

An electronically controllable fully uncoupled explicit current-mode quadrature oscillator employing Voltage Differencing Transconductance Amplifiers (VDTAs) as active elements has been presented. The proposed configuration employs two VDTAs along with grounded capacitors and offers the following advantageous features 1) fully and electronically independent control of condition of oscillation (CO) and frequency of oscillation (FO); 2) explicit currentmode quadrature oscillations; and 3) low active and passive sensitivities. The workability of proposed configuration has been demonstrated by PSPICE simulations with TSMC CMOS 0.18 μm process parameters.

Voltage-Mode and Current-Mode Resistorless Third-Order Quadrature Oscillator

“…where 20,21 . R X is the parasitic resistance of the X-terminal and g m is the transconductance gain of the CCCCTA.…”

“…The electronically tunable active components of the previous second-order oscillators include second generation current controlled conveyors (CCCIIs) [8,9]; operational transconductance amplifiers (OTAs) [10]; current differencing buffered amplifiers (CDBAs) [11,12]; the CCIITA [13]; current differencing transconductance amplifiers (CDTAs) [14][15][16][17][18][19]; multiple-output current controlled current conveyor transconductance amplifiers (MO-CCCCTAs) [20]; and voltage differencing transconductance amplifiers (VDTAs) [21]. These circuits were used to design the second-order quadrature current outputs, quadrature voltage outputs, or both quadrature current and voltage outputs.…”

Multi-function Current Differencing Cascaded Transconductance Amplifier (MCDCTA) and Its Application to Current-Mode Multiphase Sinusoidal Oscillator

“…Comparing some others active device, the outstanding features of this active element are larger dynamic range, high slew rate, electronic adjustability and low-input and high-output impedance etc. Meanwhile, from our investigations, CDTA element and its some modified devices have been widely used in analog signal processing circuit in recently years [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. However, so far, all of the reported CDTAs have two unavoidable problems: first, the transconductanse of the CDTA can not linearly tunable by controlling external bias current in a large input current range.…”

Electronically Controllable Explicit Current Output Sinusoidal Oscillator Employing Single VDTA

“…Hence, the currents (I 0 and I 01 ), (I 02 and I 01 ) and (I 03 and I 01 ) are in the quadrature form. To extract the currents I 01 , I 02 and I 03 explicitly another device with their inputs virtually grounded will be required due to which although the capacitors C 1 , C 2 and resistor R 1 will not be physically connected to ground but they will still be virtually grounded [16].…”