Novel Third-Order Quadrature Oscillators with Grounded Capacitors

Abstract

Original scientific paperThis paper presents two Current Differencing Transconductance Amplifiers (CDTA)-based current-mode resistors-less variable frequency third-order Quadrature Oscillators (TOQO). The proposed TOQOs consist of minimum number of active and passive components, especially the first TOQO, only two CDTAs and three capacitors are used in it. The two TOQOs are completely resistor-less, and the capacitors used in the TOQOs are all grounded, which are ideal for monolithic integration. The condition of oscillation (CO) and frequency of oscillation (FO) of the TOQOs can be controlled electronically and independently, which make them suitable for variable frequency oscillator (VFO). Moreover, the two TOQOs can provide four explicit quadrature current outputs at high output impedance terminals, and they can be directly cascaded with other current-mode circuits without any impedance matching requirements. Cadence IC Design Tools 5.1.41 post-layout simulation results and experimental evidence are included to confirm all the theory.Key words: Third-order quadrature oscillator, Cadence IC Design Tools, LayoutNovi kvadraturni oscilator trećeg reda s uzemljenim kondenzatorima. U ovom radu prikazana su dva kvadratična oscilatora trećeg reda (TOQO) zasnovana na strminskim pojačalima diferenciranja struja (CDTA), korištena u strujnom režimu bez otpornika uz promjenjivu frekvenciju. Predloženi TOQO-ovi sastoje se od najmanjeg mogućeg broja aktivnih i pasivnih komponenti, osobito prva inačica TOQO-a, u kojoj su korištena samo dva CDTAa i tri kondenzatora. TOQO-ovi ne posjeduju niti jedan otpornik, dok su svi kondenzatori korišteni u TOQO-ovima uzemljeni, što je idealno za monolitnu integraciju. Uvjet osciliranja (CO) i frekvencija osciliranja (FO) TOQO-ova može biti upravljana elektronički i nezavisno, što ihčini pogodnima za oscilatore promjenjive frekvencije (VFO). Nadalje, dva TOQO-a mogu isporučivatičetiri eksplicitna kvadratična strujna izlaza na priključku visoke izlazne impedancije, te mogu biti u direktnoj kaskadi s drugim krugovima u strujnom režimu bez ikakvih zahtjeva na poklapanje impedancija. Simulacijski rezultati za prikazane sheme dobiveni su korištenjem Cadence IC Design Tools 5.1.41 alata, a uključeni su i eksperimentalni pokazatelji kako bi se potvrdila sva prikazana teorijska osnova.

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

“…A survey of previously reported VM TOQSOs based on three ABBs reveals that they suffer from one or more of the following drawbacks: (i) not employing all grounded capacitors, 8,9 (ii) nonavailability of independent control of CO and FO, 8,10,12,16,24 (iii) nonavailability of output voltages from low output impedance nodes, [9][10][11][12][13][14][15][16][17][18][19] and use of ABBs that are not yet commercially available. [13][14][15][16][17][18][19]24 From the various three-ABBs-based TOQSOs, only those of the previous studies [20][21][22][23] are based upon three CFOAs, which employ all the three grounded capacitors and also provide independent control of CO and FO. However, none of the three-ABBs-based TOQSOs known earlier possess all the features that are offered by the new TOQSOs presented in this paper.…”

Systematic realization of low‐frequency third‐order sinusoidal oscillators

“…9 In open literature, various approaches have been used to realize third-order sinusoidal oscillator (TOSO) circuits. [10][11][12][13][14][15][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] The reported TOSO circuits have been designed using one of the following approaches:…”

“…30 • Oscillators in which the design approaches have not been mentioned explicitly. [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]51,53,54 The main aim of this paper is, thus, to present an approach for systematic realization of third-order LF sinusoidal oscillators (TOLFSOs) realized with minimum number of resistors and grounded capacitors with independent control of CO and FO with different resistors.…”

Low power quadrature voltage controlled oscillator

“…There are four methods to generate quadrature sinusoidal signals: RC‐CR (R stands for resistor and C stands for capacitor) phase shift method, injection‐locked frequency divider method, the current‐mode approach using active integrator, the coupling method using transformers, capacitors or MOS transistors . The RC‐CR phase shift network is very simple, and it is easy to implement.…”