New Electronically Tunable Third Order Filters and Dual Mode Sinusoidal Oscillator Using VDTAs and Grounded Capacitors

Abstract

This study introduces a third order filter and a third order oscillator configuration. Both the circuits use two voltage difference transconductance amplifiers (VDTAs) and three grounded capacitors. By selecting the input and output terminals properly, current mode and transimpedance mode low-pass and band-pass filters can be obtained without component matching conditions. The natural frequency (ω0) can be tuned electronically. The oscillator circuit provides voltage and current outputs explicitly. The condition of oscillation (CO) and the frequency of oscillation (FO) can be adjusted orthogonally and electronically. The workability of the configurations is judged using TSMC CMOS 0.18 μm technology parameter as well as commercially available LM13700 integrated circuits (ICs). The simulation results show that: for ±0.9V power supply, the power consumption is 1.08 mW for both the configurations, while total harmonic distortions (THDs) are less than 2.06% and 2.17% for the filter and oscillator configurations, respectively.

Electronically Tunable Voltage-Mode Multiphase Sinusoidal Oscillator with Low Output Impedance Nodes Employing VD-DIBAs

“…4 provides a tuning law for the FO and CO that is completely decoupled. The electronic controllability of the sinusoidal oscillator is attractive for modern circuits using microcontrollers [24]. It is easy to construct resistor R1 in each gain-controllable first-order LP filter from a photoresistor to stabilize the output amplitude level.…”

Third‐order quadrature sinusoidal oscillators with fully uncoupled tuning laws using only two CFOAs and grounded capacitors

“…The comparative features of the various two-ABBs-based TOQSOs are given in Table 1. * In third-order current-mode (CM) oscillators compared in Table 1 since both CM and VM [24][25][26][27][28][29][30][31][32][33][34] outputs have been claimed, the circuits can be cascaded when current output is taken from high impedance nodes. However, since the authors of the quoted references have also claimed their circuits to be producing voltage-mode outputs, therefore, in Table 1, the comparison has been made with these oscillators only with reference to their VM functionality, and…”

“…Table 1, thus, takes into account only the voltage-mode operability of the circuits of refs. [24][25][26][27][28][29][30][31][32][33][34]. From Table 1, it is seen that none of the ABBs in the oscillators of the quoted references are available as commercial ICs yet.…”

“…Moreover, the circuits compared in Table 1 suffer from one or more of the following drawbacks: (i) employment of all ungrounded capacitors, [37][38][39][40] (ii) nonavailability of independent control of CO and FO both, [37][38][39][40] and (iii) nonavailability of both outputs from low output impedance nodes. [24][25][26][27][28][29][30][31][32][33][34] A careful inspection of all the previously known CFOA-based TOQSO circuits of [20][21][22][23] reveals that they require three CFOAs and 4/5 resistors but do not provide fully uncoupled control of CO and FO. The main objective of this paper is to report two new realizations of CFOA-based third-order quadrature sinusoidal oscillators providing fully uncoupled control of CO and FO while employing only two CFOAs, a canonic number of four resistors and a canonic number of only three capacitors all of which are grounded.…”

“…Of late, there also has been considerable research effort on third‐order oscillators since they are expected to provide high‐quality waveforms with low harmonic distortion 2,3 . Consequently, many authors have proposed third‐order quadrature oscillators using a variety of active building blocks (ABB) such as op‐amps, operational transconductance amplifiers (OTA), current differencing transconductance amplifiers (CDTA), multiple‐input second‐generation current conveyors (MOCCII), current differencing buffered amplifiers (CDBA), operational transresistance amplifiers (OTRA), voltage differencing buffered amplifiers (VDBA), differential voltage current conveyors (DVCC), differential difference current conveyors (DDCC), current controlled current conveyors (CCCII), voltage differencing transconductance amplifiers (VDTA), multiple‐output current controlled current conveyor transconductance amplifiers (MOCCCCTA), modified current following transconductance amplifiers (MCFTA), current‐controlled current conveyor transconductance amplifiers (CCCCTA), differential voltage current conveyor transconductance amplifiers (DVCCTA), voltage differencing inverting buffered amplifiers (VDIBA), fully differential second‐generation current conveyors (FDCCII), voltage differencing current conveyors (VDCC), and many more 4–51 …”