Design Of Oscillator Research Articles

Design and Analysis of Configurable Ring Oscillators for True Random Number Generation Based on Coherent Sampling

True Random Number Generators (TRNGs) are indispensable in modern cryptosystems. Unfortunately, to guarantee high entropy of the generated numbers, many TRNG designs require a complex implementation procedure, often involving manual placement and routing. In this work, we introduce, analyse, and compare three dynamic calibration mechanisms for the COherent Sampling ring Oscillator based TRNG: GateVar , WireVar , and LUTVar , enabling easy integration of the entropy source into complex systems. The TRNG setup procedure automatically selects a configuration that guarantees the security requirements. In the experiments, we show that two out of the three proposed mechanisms are capable of assuring correct TRNG operation even when an automatic placement is carried out and when the design is ported to another Field-Programmable Gate Array (FPGA) family. We generated random bits on both a Xilinx Spartan 7 and a Microsemi SmartFusion2 implementation that, without post processing, passed the AIS-31 statistical tests at a throughput of 4.65 Mbit/s and 1.47 Mbit/s, respectively.

A Low-Power Digitally Controlled Ring Oscillator Design with IMOS Varactor Tuning Concept

A Low-Power Digitally Controlled Ring Oscillator Design with IMOS Varactor Tuning Concept

A 37 mJ, 100 Hz, high energy single frequency oscillator* *Project supported by the National Natural Science Foundation of China (Grant No. 11504389) and the Funds of Key Lab of Function Crystal and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences.

Ways on energy enhancement for single frequency oscillator are reported in this paper. By quantitative analysis on gain and loss coefficients for each cavity mode with inserted etalons, a 37 mJ, 100 Hz high energy single-frequency Nd:YAG oscillator is obtained. The pulse energy is promoted by enhancement of nearly 7 times for a single frequency oscillator reported. The result proves that this method does help for energy enhancement. It has attractive potential for high energy single frequency oscillator design, especially on condition of intensive side pumped or long cavity laser, where strong competitors exist and are hard to be suppressed.

Design of non-autonomous pH oscillators and the existence of chemical beat phenomenon in a neutralization reaction

The beat in physical systems is a transparent and well-understood phenomenon. It may occur in forced oscillatory systems and as a result of the interference of two waves of slightly different frequencies. However, in chemical systems, the realization of the latter type of the beat phenomenon has been lacking. Here we show that a periodic titration of acid and alkaline solutions with each other using programmable syringe pumps in a continuous stirred-tank reactor exhibits the beat phenomenon in the temporal pH oscillation pattern if the time periods of sinusoidal inflow rates of the reagents are slightly different. Interestingly, the frequency of the chemical beat pattern follows the well-known relationship from physics, namely the frequency of the beat is equal to the absolute value of the difference of the two wave frequencies. Based on our strategy, we can design and engineer non-autonomous pH oscillatory systems, in which the characteristics of the temporal oscillations (amplitude, time period) can easily and precisely be controlled by the experimental conditions such as the inflow rates and feed concentrations. The demonstrated phenomena can be exploited in practical applications, we use the non-autonomous pH oscillators to drive the reversible assembly and disassembly of pH-sensitive building blocks (oleic acid and gold nanoparticles), both highly relevant in nanotechnology and biomedical applications.

Vortex gyrotropic mode in curved nanodots

In this work, we present the influence of the curvature of magnetic nanodot on the vortex gyrotropic mode frequency. We show that gyrotropic oscillation of the magnetic vortices is highly influenced by the rounding of the nanodot shape due to the formation of the apex and single domain state in the upper part of the dot. The curved shape of nanodot could arise during the fabrication process of the nanodots, i.e., during lithography. We find that strong dependence of the gyrotropic mode frequency on curvature parameter is related to magnetic phase transition: from vortex to out-of-plane state. The found effect can be used, e.g., for the design of the spin torque nano oscillators.

A systematic approach for the design of linear filters and oscillators employing tree representation

A systematic approach for the design of linear filters and oscillators employing tree representation

A design of nanoscale double-gate FET based ring oscillator with improved oscillation frequency using device engineering

In this paper, the performance of inverter and ring oscillator circuits based on the nanoscale double-gate (DG) FET is improved by using device engineering approaches. The modification of the parameters affecting the intrinsic delay time of the DGFET, such as on-current and the total gate capacitance can be improved the oscillation frequency of the ring oscillator. Accordingly, the effects of gate oxide thickness (tox) and body thickness (tbody) on the electrical characteristics of the device and circuit-level have been investigated so that we could provide a design of ring oscillator with improved oscillation frequency. Moreover, the enhanced source doping concentration and graded-channel (GC) techniques have been applied and analyzed at the device-level to ameliorate the oscillation frequency of the ring oscillator. Finally, we have presented the graded-channel (GC) strategy with two types of high-low (HL) and low-high (LH). The extracted results illustrate that the total gate capacitance of the LH-GC-DGFET is improved significantly compared to the HL-GC-DGFET. Consequently, the efficient design of the ring oscillator based on LH-GC-DGFET with superior oscillation frequency is proposed. The TCAD mixed-mode simulation has been used for simulating the circuits.

A Novel Approach for Low Phase Noise Voltage Controlled Oscillator Design based on TSMC 0.18 um Technology

In this paper, a new structure of Voltage Control Oscillator (VCO) to reduce the phase noise using two plans of a variable voltage capacitor is proposed. The aim of the current paper is to analyse two structure of a completely integrated 3.7 GHz LC-VCO based on TSMC 0.18 um technology. In the first plan for different voltages with variable voltage capacitors in this circuit can be achieved to a suitable phase noise of about 125 dB per Hz and in the second plan, a noise of -123 dB per Hz is achieved in the deviation frequency of 1 MHz. Also, the Figure of Merit (FOM) values for the first plan of -4/186 and for the second plan of –4/184 are achieved and the power consumption is 10 mW.

Modified Modeling Method of Quartz Crystal Resonator Frequency-Temperature Characteristic With Considering Thermal Hysteresis.

The frequency-temperature ( f - T ) characteristic of quartz crystal resonators is an important topic closely related to the frequency-deviation compensation in the design of cost-effective oscillators. Traditional studies depict the f - T characteristic as a polynomial function (usually a cubic function). However, this omits the thermal hysteresis phenomenon and cannot provide a very accurate frequency compensation. To handle this issue, this article is to propose two modified f - T characteristic modeling methods with considering the thermal hysteresis. First, to reflect the thermal hysteresis property of quartz crystal resonators, a two-directional f - T model is designed by introducing two individual submodels for describing the increasing and decreasing temperature stages, respectively. Furthermore, to integrate the submodels and provide the more accurate frequency-deviation estimation, a holistic f - T characteristic model based on double-hidden layer extreme learning machine (DHL-ELM) is presented. Different from the basic ELM model, two hidden layers, including one deterministic nonlinear mapping and one random nonlinear activation layer, are constructed for a better description of f - T characteristic. To validate our studies, an experiment system is applied to obtain the testing data of the real crystal resonators, and the applications demonstrate the effectiveness of the proposed methods.

Raman suppression in a high-power single-mode fiber oscillator using a chirped and tilted fiber Bragg grating

We propose the design of a high-power fiber oscillator with chirped and tilted fiber Bragg gratings (CTFBGs) to suppress the stimulated Raman scattering within the fiber cavity and in the delivery fibers. A high-power single-mode fiber oscillator system was constructed for demonstration. With a CTFBG inserted into the fiber cavity, obvious Raman suppression was observed and the output signal laser power increased by ∼7%. With a CTFBG inserted between the oscillator and the delivery fibers, a maximum Raman suppression ratio of >20 dB was achieved, which implies a longer delivery distance for the same laser power level. By further improving the performance of CTFBGs, including lower inversion loss at signal wavelength, wider rejection bandwidth and deeper rejection depth, meanwhile optimizing the positions of CTFBGs, better Raman suppression could be obtained, which is significant for the further power scaling and delivery distance increasing of high-power fiber oscillators.

Pinning and rotation of a skyrmion in Co nanodisk with nanoengineered point and ring defects.

Magnetic skyrmions have been proposed as promising information carriers in the application of spintronics, while the material imperfections are inevitable, thus an understanding of pinning effects on skyrmions in confined geometry is crucial for both fundamental research and development of spintronic devices. Here, we present the interactions of a skyrmion with a point and an extended ring defect, in a Co nanodisk which can be applied in skyrmion oscillator, based on micromagnetic simulations. By comparing with the skyrmion preferred position which is in the nanodisk center without defects, we identify the pinning strength and skyrmion preferred positions with a point defect as a function of skyrmion-defect distance and different local parameters of defect region being considered. The pinning centers range from skyrmion center, domain wall and off-center regions. We find a confinement effect on the skyrmion size with a ring defect. Moreover, we also show the rotation of the skyrmion in the presence of a ring defect, that can lead to a variation of oscillation frequency in a large range. These findings provide a complete understanding of the interaction between skyrmion and defects in a nanodisk and may provide a guidance for the design of skyrmion oscillators.

Electronically tunable higher-order quadrature oscillator employing CDBA

A higher-order Quadrature Sinusoidal Oscillator (QSO) topology using Current Differencing Buffered Amplifier (CDBA) as an active device is investigated. The proposed oscillator produces two sinusoidal variable frequency waveforms with 90° of phase shift and suitable for signal processing applications. An unambiguous electronic control in terms of a performance parameter of oscillator such as the condition of oscillation and frequency of oscillation can be successfully achieved by using grounded and virtually grounded passive components in our proposed quadrature oscillator design. To demonstrate the feasibility of the proposed quadrature circuit, both transient and frequency response outputs are well observed through PSPICE in which CDBA is integrated with 0.18 ​μm CMOS technology parameter. In addition, hardware verification is also executed using commercially accessible Current Feedback Operational Amplifier (CFOA) as IC AD844AN and standard passive components. The other performance analysis such as sensitivity, non-ideality effect, frequency stability, phase noise, temperature analysis and Monte-Carlo analysis are also discussed for the proposed structure. The layout of the proposed configurations is also observed using the Analog Design Environment (ADE) spectra tool provided by Cadence Virtuoso.

Automated Biocircuit Design with SYNBADm.

SYNBADm is a Matlab toolbox for the automated design of biocircuits using a model-based optimization approach. It enables the design of biocircuits with pre-defined functions starting from libraries of biological parts. SYNBADm makes use of mixed integer global optimization and allows both single and multi-objective design problems. Here we describe a basic protocol for the design of synthetic gene regulatory circuits. We illustrate step-by-step how to solve two different problems: (1) the (single objective) design of a synthetic oscillator and (2) the (multi-objective) design of a circuit with switch-like behavior upon induction, with a good compromise between performance and protein production cost.

Radial Waves Propagation in a Single-Walled Carbon Nanotube with Surface Irregularity

This work is an attempt to study the propagation of radial waves in an irregular single-walled carbon nanotube (ISWCNT). The characteristics equation of phase velocity of radial waves is derived using cylindrical thin shell theory. Taking into account the effects of the surface irregularity, dispersion curves are plotted and the effectiveness of surface irregularity is confirmed by comparing the obtained numerical results with those in cases of propagation of radial waves in uniform nanotube. The results turn out that, the phase velocity of radial waves is dependent on the surface irregularity and it is increasing with an increase of surface irregularity parameter. To the author best knowledge, propagation of radial waves in the irregular single-walled carbon nanotubes has not yet been studied, and the present work is an attempt to find out the dispersion relation of radial waves in ISWCNTs. Finally, the present results may serve as useful references for the application and the design of nano oscillators and nanodevices, in which single-walled carbon nanotubes act as the most prevalent nanocomposite structural element.

A Novel Varactorless Tuning Technique for Clapp VCO Design Using Tunable Negative Capacitor to Increase Frequency-Tuning Range

In this paper, a varactorless frequency-tuning method for Clapp voltage-controlled oscillator (VCO) design is proposed aiming at increasing frequency-tuning range (FTR) in comparison with the conventional varactor-based counterpart. The proposed structure uses a tunable non-Foster (negative) capacitor (TNC) to sweep oscillation frequency instead of a varactor. The analytical demonstration points that total tuning dynamic (TTD) qualitatively representing FTR is traditionally limited to varactor’s tuning dynamic (TD); while the TNC-based VCO can exhibit very-high TTD, at least over TNC’s TD capacity, if the maximum negative capacitance is appropriately designed, which can tolerate the TD requirement on the tuning component for wideband operation. Circuit realization of TNC is based on a grounded negative impedance inverter (NII) with cross-coupled transistors whose gate voltage controls capacitance. A simulation script using a real discrete transistor model with the realized TNC shows that FTR can be covered with TTD of 2.46 units while the TD of the non-Foster tuning component is only 1.32 units, validating the advantageous operation as well as practical realization possibility of the proposed VCO. In addition, phase noise performance is remained below −100 dBc/Hz for every tuning voltages at 1 MHz offset frequency, while figure of merit comprising FTR effect (FOMT) can be achieved in range of 140-180, which is similar to the existing state-of-the-art VCOs.

Синхронизация генераторов на ЛПД импульсного и непрерывного действия в мм-диапазоне длин волн. Часть 2. Стабилизация СВЧ-параметров синхронизированных генераторов

This is the second part of the two-part article, which summarizes the state-of-the-art results in the development of synchronized oscillators based on IMPATT (IMPact ionization Avalanche Transit-Time) diodes. The first part of the paper presented the electrodynamic design of oscillators, which contain a resonant oscillatory system with silicon IMPATT diodes and are synchronized by an external source of microwave oscillations. The second part of the paper considers the methods for stabilizing the parameters of IMPATT oscillators, which make it possible to create coherent power sources in the millimeter wavelength range. The specifics of pulse generators lies in the change in frequency within the microwave pulse relative to the change in temperature, which leads to a change in the impedance of the diode and thus to a phase change with respect to the synchronizing signal. Phase modulation is reduced or completely eliminated (which is necessary to ensure the coherence of the microwave transmitter) by using current compensation, i.e., by using the control current pulse with a special shape. The study demonstrates the expediency of introducing additional heating of the semiconductor structure of the IMPATT diode, which allows the initial temperature of the IMPATT diode in the region of the leading edge of each pulse to remain virtually constant and independent of the ambient temperature. Using these methods on silicon double-drift IMPATT diodes allowed creating synchronized oscillators with high frequency stability and an output power level from 20 to 150 W, which have a high degree of coherence in the synchronization mode with an external signal. The paper also presents the designs and parameters of coherent microwave power sources in the short-wave part of the millimeter wavelength range using the nonlinear properties of the IMPATT diodes in the radio-pulse conversion mode. This mode makes it possible to provide the output power level of the signal at the n-th harmonic Pout ≈1/n, which significantly exceeds the achieved characteristics of the frequency multipliers with charge accumulation, where Pout ≈ 1/n2. The output power of such devices is achieved at the level of 50–20 mW in the 75–180 GHz frequency range with a frequency multiplication factor of 1–15.

Numerical simulation of the transient behavior of the turbulent flow in a microfluidic oscillator

In this study, the transient numerical simulation of the flow in a fluidic oscillator has been performed. The proposed device includes several geometrical modifications of a previously patented apparatus intended for the synthesis of ozone-rich bubbles in an oxygen plasma. Prior to the experimental construction of the proposed fluidic oscillator, the present work performs a numerical study of the internal flow in the proposed design, aimed to determine its feasibility. The unsteady simulations are based on the unsteady Reynolds averaged Navier–Stokes equations coupled to the transition Shear Stress Transport (transition SST) turbulence model due to the low Reynolds numbers considered (3500 and 5000 based on flow bulk velocity). The behavior of the complex fluid flow inside the device, where four main vertical structures develop and interact, along one cycle is described in detail including the turbulent kinetic energy and intermittency in the analysis. Moreover, the effect of increasing the Reynolds number on the pressure oscillation frequency and amplitude is analyzed. In particular, the frequency is increased around a 38% and the amplitude a 100% when switching from a Reynolds number of 3500–5000. The numerical results obtained are encouraging, and the evaluated fluidic oscillator design will be fabricated and analyzed in an upcoming experimental study.

Vibrational analysis of an irregular single-walled carbon nanotube incorporating initial stress effects

AbstractIn this work, an attempt is done to apply the eigenvalue approach as well as Donnell thin-shell theory to find out the vibrational analyses of an irregular single-walled carbon (ISWCNT) incorporating initial stress effects. The effects of surface irregularity and initial stresses on natural frequency of vibration of nano materials, especially for single-walled carbon nanotubes (SWCNTs), have not been investigated before, and most of the previous research have been carried for a regular and initial stress-free CNTs. Therefore, it must be emphasized that the vibrations of prestressed irregular SWCNT are novel and applicable for the design of nano oscillators and nanodevices, in which SWCNTs act as the most prevalent nanocomposite structural element. The surface irregularity is assumed in the parabolic form at the surface of SWCNT. A novel equation of motion and frequency equation is derived. The obtained numerical results provide a better representation of the vibration behavior of prestressed ISWCNTs. It has been observed that the presence of either surface irregularity or initial stress has notable effects on the natural frequency of vibration, particularly in the short-length SWCNTs. Numerical results show that the natural frequency of SWCNT decreases with increase in surface irregularity and initial stress parameters. To the authors’ best knowledge, the effect of surface irregularity and initial stresses on the vibration behavior of SWCNTs has not yet been studied, and the present work is an attempt to find out this effectiveness. In addition, the results of the present analysis may serve as useful references for the application and the design of nano oscillators and nanodevices, in which SWCNTs act as the most prevalent nanocomposite structural element.

Analysis and Design of 460 GHz Microwave Gyrotron Oscillator

This paper is concerned with the analysis and design of a gyrotron oscillator with 460 GHz that can excite both modes (TE231) the fundamental (230GHz) and (TE061, TE261) second harmonic (near 460GHz). The oscillator is operated with 12KV beam voltage and 100mA beam current, and a computer program was developed to study the cavity in this oscillator and the wave-particle interaction inside it using the forward finite difference technique as a numerical method. The input data of the program are electron energy, velocity ratio, normalized cavity length, the normalized value of the external magnetic field, the mode number (m,n,l), and nth-non van shining root of J_m^' (x)=0 to calculate the beam and starting currents, frequency and quality factor of the cavity. The results show good agreement with other reported works [10]- [12]- [13]- [14], [15] .This oscillator can serve as a millimeter-wave source at the magnetic field of (16.4T) for enhanced nuclear magnetic resonance and can be used to perform the biological experiment.

A large-scale comprehensive evaluation of single-slice ring oscillator and PicoPUF bit cells on 28-nm Xilinx FPGAs

Lightweight implementation of security primitives, e.g., physical unclonable functions (PUFs) and true random number generator, in field programmable gate array (FPGA) is crucial replacement of the conventional decryption key stored in battery-backed random access memory or E-Fuses for the protection of field reconfigurable assets. A slice is the smallest reconfigurable logic block in an Xilinx FPGA. The entropy exploitable from each slice of an FPGA is an important factor for the design of security primitives. Previous research has shown that the locations of slices can impact the quality of delay-based PUF designs implemented on FPGAs. To investigate the effect of the placement of each single-bit PUF cell free from the routing resource constraint between slices, single-bit ring oscillator (RO) and identity-based PUF design (Pi-coPUF) cells that can each be fully fitted into a single slice are evaluated. To accurately evaluate their statistical performance, data from a large number of devices are required. To this end, 217 Xilinx Artix-7 FPGAs has been employed to provide a large-scale comprehensive analysis for the two designs. This is the first time single-slice disorder-based security entities have been investigated and compared on 28-nm Xilinx FPGA. Uniqueness, uniformity, correlation, reliability, bit-aliasing and min-entropy of each type of cell are evaluated for four different types of cell placement. Our experimental results corroborate that the location of both cell types in the FPGA affects their performances. For both cell types, the lower the correlation between devices, the higher the min-entropy and uniqueness. Overall, the min-entropy, correlation and uniqueness of PicoPUF are slightly higher than those of RO. Otherwise, the uniformity, bit-aliasing and reliability of the PicoPUF are slightly lower than those of the RO. Comparing the resource usage and metrics of the PicoPUF, ring oscillator PUF and some existing memory-based PUF implementations, PicoPUF stands out as a lightweight FPGA-based weak PUF design. The raw data for the PicoPUF design are made publicly available to enable the research community to use them for benchmarking and/or validation.