Proposed Oscillator Circuit Research Articles

Development of Two-Stage Quartz-Crystal Oscillators Using Monolithic Four-Terminal CFOAs

In this article, based on the well-known circuits of two-stage quartz-crystal oscillators, three electronic circuits with a small number of external components are presented. For the proposed circuit configurations, the active elements are composed of monolithic current-feedback operational amplifiers (CFOAs) with access to terminal z, between the first stage (positive second-generation current conveyor (CCII)) and the second stage (output buffer). In this way, the output signal for the developed circuits is obtained after the output buffer of the second CFOA, thereby providing a minimal effect on the resonant circuit of the oscillators. Based on a theoretical analysis of the operational principle for the proposed circuits, the linear characteristic equations and the related self-oscillation conditions are obtained. Moreover, the frequency stability coefficients are determined, which can be obtained with larger values compared to the coefficients of the known discrete transistor circuits. To verify the operability and efficiency of the proposed oscillator circuits, experimental results obtained from sample electronic circuits are presented, which confirm the analyses performed in the frequency range up to about 10 MHz.

A new high frequency MOS-C TOETQO employing DXCCTA

ABSTRACT This research paper reports a high frequency Third Order Electronically Tunable Quadrature Oscillator (TOETQO) using an active element termed as Dual-X Current Conveyor Transconductor Amplifier (DXCCTA) in which active element MOS and passive Capacitor (C) contribute the implementation performance of the proposed design as MOS-C TOETQO. Due to the presence of DXCCTA with active grounded capacitor and MOS-based resistor, the proposed quadrature oscillator facilitates a suitable design for integrated circuits (ICs). The proposed TOETQO circuit produces current as well as voltage outputs simultaneously. Moreover, the non-ideal analysis of the proposed oscillator circuit is also included. The proposed design shows a good agreement for the oscillation criteria due to the acceptable limit of %THD and gives the variation in frequency of oscillation (up to MHz) values with respect to bias current. Moreover, by keeping the bias current constant, frequency of oscillation can also be electronically tuned independently by varying the values of resistor. Finally, Cadence simulation results are depicted to verify the theoretical analyses and practical feasibility of proposed TOETQO design is also well verified with experimental set up by using IC AD844 and CA3080. A fair comparison of the proposed quadrature oscillator with existing literatures is also tabulated.

Radiation-Tolerant Digitally Controlled Ring Oscillator in 65-nm CMOS

This article presents a radiation-tolerant digitally controlled complementary metal&#x2013;oxide&#x2013;semiconductor (CMOS) ring oscillator design suitable for all-digital phase-locked loop (ADPLL) implementations. To address the challenges presented by harsh radiation environments, a wide tuning range oscillator architecture is presented with superior single-event effect (SEE) tolerance. The proposed oscillator circuit is characterized experimentally in a 65-nm technology and shown to achieve a significant reduction in SEE sensitivity up to a linear energy transfer (LET) of 63.5 MeVmg<inline-formula> <tex-math notation="LaTeX">$^{-1}$ </tex-math></inline-formula>cm², remain free from harmonic oscillation errors under irradiation, and withstand a total radiation dose exceeding 1.5 Grad. At the design frequency of 1.28 GHz, the oscillator dissipates 7 mW of power while achieving a phase noise of &#x2212;105 dBc/Hz at 1 MHz offset, corresponding to a figure of merit (FOM) of 159 dB.

A Linear VCO Using Single CFA and Analog Multipliers: Quadrature Oscillator Implementation

A new linear voltage-controlled oscillator (LVCO) implementation using single AD-844 CFA with a pair of AD-835 multiplier devices and a pair of grounded capacitors is proposed. The open-loop transfer function of the topology is analyzed wherein the concept of Short-Circuit Natural Frequency (SCNF) is applied to derive the sinusoid oscillator implementation. The proposed oscillator circuit is then restructured to yield a linear voltage-controlled quadrature oscillator (LVCQO) after appropriate cascade with a CFA-based active integrator. The oscillation frequency is linearly tunable ([Formula: see text][Formula: see text]MHz) by the multiplier control voltage ([Formula: see text]. Subsequently, a high-[Formula: see text] selective band-pass (BP) filter is derived. Effects of the CFA port roll-off parameters and its parasitic capacitors ([Formula: see text] had been analyzed to be negligible. Measured oscillator response exhibited a THD [Formula: see text]%, a linearity error ([Formula: see text]% and a phase noise figure of ([Formula: see text]104 dBc/Hz at 24-kHz offset.

Quadrature Sinusoidal Oscillators Using CDBAs: New Realizations

Four new circuits of fully uncoupled quadrature sinusoidal oscillators, using two current differencing buffered amplifiers (CDBAs), four/five resistors and two capacitors have been presented. In contrast to all previously published CDBA-based, fully decoupled, quadrature sinusoidal oscillators in which one of the input terminals is left unutilized, the presented circuits are realized by utilizing the intrinsic current differencing property of CDBAs, thus utilizing all the four terminals of the CDBA. All these quadrature oscillator (QO) circuits have an inherent feature of amplitude control of output voltages without using external control circuitry. Out of the four proposed QO circuits, two circuits have the additional feature of generating low-frequency oscillations, thus making them capable of generating wide range of frequency waveforms. The proposed oscillator circuits also possess additional functionalities not available in other CDBA-based quadrature sinusoidal oscillator circuits presented previously. The workability of the proposed circuits has been confirmed through experimental results where CDBAs are implemented using commercially available current feedback operational amplifiers (AD844).

VDCC Based Sinusoidal Oscillators Using All Grounded Capacitors: A Series of Realization

A series of eight new current mode sinusoidal oscillators employing a versatile and less explored active element, i.e., voltage differencing current conveyor, is presented in this manuscript. All the derived oscillators provide an explicit current output from their high impedance port. Enumerated circuits require only a single active element, two grounded capacitors, and two passive resistors. Amongst all newly proposed oscillator circuits, two configurations utilize only grounded passive elements and can simultaneously provide explicit current quadrature outputs. The condition and frequency of oscillation, in all cases, are simple and orthogonal. All regular mathematical analysis, such as non-ideal, sensitivity and parasitic, are presented to support the design ideas.In addition to the experimental results performed using commercially available integrated circuits, software simulation results of all the proposed circuits have also been included in the manuscript. In the former case the range of frequencies, for the designed oscillators, as low as 349 kHz and as high as 2.64 MHz where as the experimental range of frequencies lies in the span of 192 kHz to 5.8 MHz. The best figure for total harmonic distortion can be found as low as 1.2% for oscillator no. 8.

Electronically controllable third-order quadrature sinusoidal oscillator employing CMOS-OTAs

This paper describes a voltage mode third-order quadrature sinusoidal oscillator (TOQSO) based on operational transconductance amplifiers (OTAs). The proposed configuration uses three OTAs and three grounded capacitors. Outputs of two voltage mode sinusoids with 90° phase difference are found in the proposed oscillator circuit. The condition of oscillation and frequency of oscillation are independently electronically controllable by separate transconductances of the OTAs. The performance of TOQSO is tested by SPICE (version 16.5) simulation using TSMC 0.18 µm technology parameters and experimental results employing CA3080 type IC OTAs have been presented to confirm the workability of the proposed new configuration.

A compact low-phase noise oscillator with superior harmonic suppression characteristics based on novel nested split-ring resonator (NSRR)

In this paper, a novel microwave oscillator incorporating miniaturized nested split-ring resonators is proposed. The high-quality (Q) factor and wide spurious-free band of the NSRR contribute to low-phase noise and high-harmonic suppression of the proposed oscillator circuits. In addition, the NSRR is featured by compact size of 0.12λg × 0.12λg, where λg is the guided wavelength of resonance frequency. The fabricated 2.4 GHz oscillator has an output power of 11.7 dBm with 5 V DC supply and 10 mA current consumption. The second harmonic suppression is −45.49 dBc, the phase noise is −110 dBc/Hz @100 kHz, and the DC–RF conversion efficiency is measured as 30%.

A 32 mV/69 mV input voltage booster based on a piezoelectric transformer for energy harvesting applications

This paper presents a novel method for battery-less circuit start-up from ultra-low voltage energy harvesting sources. The approach proposes for the first time the use of a Piezoelectric Transformer (PT) as the key component of a step-up oscillator. The proposed oscillator circuit is first modelled from a theoretical point of view and then validated experimentally with a commercial PT. The minimum achieved start-up voltage is about 69mV, with no need for any external magnetic component. Hence, the presented system is compatible with the typical output voltages of thermoelectric generators (TEGs). Oscillation is achieved through a positive feedback coupling the PT with an inverter stage made up of JFETs. All the used components are in perspective compatible with microelectronic and MEMS technologies. In addition, in case the use of a ∼40μH inductor is acceptable, the minimum start-up voltage becomes as low as about 32mV.

New Voltage Mode Sinusoidal Oscillator Using Voltage Differencing Transconductance Amplifiers (VDTAs)

The purpose of this paper is to introduce a new electronically controlled voltage mode sinusoidal oscillator (VMSO) using Voltage Differencing Transconductance Amplifiers (VDTA). The proposed circuit provides electronic control of ω0 and independent condition of oscillation (CO). It is found that the oscillator works very satisfactorily and pure sinusoidal waveforms are available at the outputs. The PSPICE simulation confirms the theoretical results. The proposed oscillator circuit employs only two VDTAs, along with two grounded capacitor and single grounded resistor. The circuit exhibits low active and passive sensitivities for ω0. Simulation results are obtained by using PSPICE software with TSMC CMOS 0.18 um process parameters.

New Realizations of Single OTRA-Based Sinusoidal Oscillators

This study proposes three new sinusoidal oscillators based on an operational transresistance amplifier (OTRA). Each of the proposed oscillator circuits consists of one OTRA combined with a few passive components. The first circuit is an OTRA-based minimum RC oscillator. The second circuit is capable of providing independent control on the condition of oscillation without affecting the oscillation frequency. The third circuit exhibits independent control of oscillation frequency through a capacitor. This study first introduces the OTRA and the related formulations of the proposed oscillator circuits, and then discusses the nonideal effects, sensitivity analyses, and frequency stability of the presented circuits. The proposed oscillators exhibit low sensitivities and good frequency stability. Because the presented circuits feature low impedance output, they can be connected directly to the next stage without cascading additional voltage buffers. HSPICE simulations and experimental results confirm the feasibility of the new oscillator circuits.

CMOS realization of single-resistance-controlled and variable frequency dual-mode sinusoidal oscillators employing a single DVCCTA with all-grounded passive components

In this paper, two new designs are proposed for sinusoidal oscillators based on a single differential voltage current conveyor transconductance amplifier (DVCCTA). Each of the proposed circuits comprises a DVCCTA combined with passive components that simultaneously provides both voltage and current outputs. The first circuit is a DVCCTA-based single-resistance-controlled oscillator (SRCO) that provides independent control of the oscillation condition and oscillation frequency by using distinct circuit parameters. The second circuit is a DVCCTA-based variable frequency oscillator (VFO) that can provide independent control of the oscillation frequency by adjusting the bias current of the DVCCTA. In this paper, the DVCCTA and relevant formulations of the proposed oscillator circuits are first introduced, followed by the non-ideal effects, sensitivity analyses, frequency stability discussions, and design considerations. After using the 0.35-μm CMOS technology of the Taiwan Semiconductor Manufacturing Company (TSMC), the HSPICE simulation results confirmed the feasibility of the proposed oscillator circuits.

First CFOA-based explicit-current-output quadrature sinusoidal oscillators using grounded capacitors

To date, no current-feedback operational amplifier (CFOA)-based sinusoidal oscillator has been reported which provides all the following features simultaneously: (i) current-mode quadrature sinusoidal oscillator providing two explicit-current-outputs (ECOs) from high output impedance terminals, (ii) employing no more than three CFOA ICs and six passive components, which include two grounded capacitors, (iii) offers independent tuning of the condition of oscillation (CO) via a resistor and (iv) provides tunability of the ratio of amplitudes of the generated quadrature ECOs via a separate resistor. To the best of authors' knowledge, this article reports first CFOA-based QOs in current-mode (i.e. providing two ECO signals). Experimental results using AD844 CFOA ICs from Analog Devices have been included to verify the workability of the proposed oscillator circuits. An example automatic gain control (AGC) loop to regulate the oscillation amplitude and control the THD has also been used and verified using SPICE simulations using the AD844 macro-model.

Dual-mode resistorless sinusoidal oscillator using single CCCDTA

This study proposes a new design for a resistorless second-order sinusoidal oscillator. The proposed circuit uses a single current-controlled current-differencing transconductance amplifier (CCCDTA) and two capacitors to perform the functions of a resistorless sinusoidal oscillator. The proposed oscillator provides a voltage output and a current output simultaneously, and can independently control the oscillation condition and oscillation frequency by using the separate bias currents of the CCCDTA. This study first introduces the CCCDTA and the related formulations of the proposed oscillator circuit, and then presents the non-ideal effects, sensitivity analyses, and design considerations of the proposed circuit. The proposed oscillator features a compact topology and dual-mode operation, including low active and passive sensitivities, and has high potential for integration because it is composed of a single CCCDTA and two capacitors. The HSPICE simulation results in this study confirm the feasibility of the new resistorless oscillator circuit. Graphical abstractThis paper proposes a CCCDTA-based dual-mode resistorless sinusoidal oscillator. The proposed circuit uses a single current-controlled current-differencing transconductance amplifier (CCCDTA) and two capacitors to perform the functions of a resistorless sinusoidal oscillator. The proposed oscillator provides a voltage output and a current output simultaneously, and can independently control the oscillation condition and oscillation frequency by using the separate bias currents of the CCCDTA. The HSPICE simulation results in this study confirm the feasibility of the new resistorless oscillator circuit. CCCDTA-based dual-mode resistorless sinusoidal oscillator. [Display omitted] Highlights► This study presents a dual-mode resistorless sinusoidal oscillator using single CCCDTA. ► The proposed circuit uses a single CCCDTA and two capacitors. ► The oscillation condition and oscillation frequency of the circuit can be independently adjusted.

Analog CMOS circuit implementation of a pulse-coupled phase oscillator system and observation of synchronization phenomena

Analog CMOS circuit implementation of a system of pulse-coupled phase oscillators is proposed. A CMOS circuit that achieves the dynamics of pulse-coupled oscillators has been designed and fabricated using a 0.25-µm CMOS technology. The proposed oscillator circuits with continuous-time operation interact with each other via a pulse at each firing time. Update of the oscillator state is achieved by integrating the phase sensitivity function with the pulse width time span. The phase sensitivity function is generated by the combination of binary functions, while the function consists of three-values {-1,0,1}. Introducing a zero-value span in the function leads to fast synchronization and robustness to parameter fluctuation due to LSI device mismatches, which facilitates VLSI implementation. Using the fabricated CMOS circuit, we have observed not only in- and anti-phase but also out-of-phase synchronization.

Resistorless dual-mode quadrature sinusoidal oscillator using a single active building block

This paper presents a new realization of resistorless mixed-mode (i.e. both voltage-mode and current-mode) quadrature sinusoidal oscillator using a new active building block (ABB) called the differential voltage current-controlled conveyor transconductance amplifier (DVCCCTA). The proposed oscillator circuit uses a single DVCCCTA, two grounded capacitors (GCs) and does not employ any external linear resistors. The tuning laws for the condition of oscillation (CO) and the frequency of oscillation (FO) are non-interactive; and controlled by separate bias currents. The circuit provides two explicit quadrature current outputs and two quadrature voltage outputs and thus can be classified as a mixed-mode quadrature oscillator. Another notable feature of the proposed circuit is that it can also be used as a biquadratic filter to realize low-pass and band-pass filtering functions simultaneously. Non-ideal analysis of the circuit is provided and PSpice simulation results have been included to verify the workability of the proposed circuit.

Electronically tunable multiphase sinusoidal oscillator using translinear current conveyors

A new electronically tunable current-mode multiphase sinusoidal oscillator based on translinear current conveyors is presented. The proposed oscillator circuit, which employs only one translinear current conveyor and one grounded capacitor for each phase, can generate arbitrary N output current equal-amplitude signals that are equally spaced in phase (N being even or odd), all at high output impedance terminals. The frequency of oscillation and the condition of oscillation can be controlled electronically and independently through the bias current of the translinear current conveyor. The proposed structure also has simple circuitry, low-component count, and is highly suitable for integrated circuit implementation. The theoretical results were verified by PSPICE simulation. In addition, the modification of the N sinusoidal oscillators to construct a programmable multiphase oscillator is also discussed.

Current-Mode Multiphase Sinusoidal Oscillator Using Current Differencing Transconductance Amplifiers

This paper describes a simple current-controlled current-mode multiphase sinusoidal oscillator based on current differencing transconductance amplifiers (CDTAs) as active components. The proposed oscillator circuit, which employs only one CDTA and one grounded capacitor for each phase, can generate arbitrary n current-output signals (n being even or odd) equally spaced in phase, all at high output impedance terminals. The oscillation condition and the oscillation frequency can be controlled electronically and independently through the bias current of the CDTA. The oscillator has low-component count, low-sensitivity performance, and is highly suitable for monolithic implementation. PSPICE simulation results are given to confirm the operation of the proposed oscillator.

A new phase noise reduction method of oscillator by loaded Q improvement using dual feedback topology

This letter presents a new method to reduce the phase noise in oscillator based on the loaded Q improvement approach. A hairpin resonator is weakly coupled to the two microstrip lines to improve the loaded Q of it and the dual feedback topology is used to enable the start-up oscillation condition to be satisfied. The high loaded Q property of the resonator in the proposed oscillator circuit is analyzed using the CAD simulation. For comparison the phase noise performances of the conventional hairpin resonator oscillator and the oscillator using the dual feedback are measured. Measurements show that the oscillator using the dual feedback exhibits a low phase noise performance of -109.1 dBc/Hz at 100-kHz offset at 10 GHz, which is reduced by about 10 dB compared to that of the conventional one.

A new CCII-based sinusoidal oscillator providing fully independent control of oscillation condition and frequency

In this paper, a new CCII-based double-resistance controlled sinusoidal oscillator employing grounded resistors and capacitors is presented. The oscillator topology provides fully independent control of oscillation conditions and oscillation frequency, and suitability for VLSI realization due to including only grounded passive elements. The circuit exhibits low active and passive sensitivities; voltage and current tracking error effects on the current conveyors can easily be eliminated with careful design. Moreover, a methodology for determination of linear operation conditions of the oscillator is studied. For the proposed oscillator circuits, the maximum output signal level not causing clipping and the slew-rate-limiting problem is determined using a simple formula. Theoretical results are confirmed with both PSPICE simulations and experimental results.