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• A new realization of the fractional capacitor using passive symmetric networks is proposed. • General analysis of this network regardless of the internal impedances composition is introduced. • Three scenarios based on RC circuit or integer Cole-Impedance circuit or both are utilized. • The network size is optimized using Minimax and least m th optimization techniques. • Monte Carlo simulations and experimental results are provided with applications. In this paper, a new realization of the fractional capacitor (FC) using passive symmetric networks is proposed. A general analysis of the symmetric network that is independent of the internal impedance composition is introduced. Three different internal impedances are utilized in the network to realize the required response of the FC. These three cases are based on either a series RC circuit, integer Cole-impedance circuit, or both. The network size and the values of the passive elements are optimized using the minimax and least m th optimization techniques. The proposed realizations are compared with well-known realizations achieving a reasonable performance with a phase error of approximately 2 o. Since the target of this emulator circuit is the use of off-the-shelf components, Monte Carlo simulations with 5 % tolerance in the utilized elements are presented. In addition, experimental measurements of the proposed capacitors are preformed, therein showing comparable results with the simulations. The proposed realizations can be used to emulate the FC for experimental verifications of new fractional-order circuits and systems. The functionality of the proposed realizations is verified using two oscillator examples: a fractional-order Wien oscillator and a relaxation oscillator. [ABSTRACT FROM AUTHOR]

This paper investigates relation between injection signaling and the lock range of relaxation oscillators. We show that lock range is determined by the effective injection signals of Volterra circuits contributed by both external injection signals and the nonlinearity of oscillators. The larger the harmonic tones of injection signals and the higher the degree of the nonlinearity of oscillators, the larger the effective injection signals subsequently the larger the lock range. We further show in order to maximize the contribution of external injection signals, injection phase needs to be π / 2 , valid for oscillators with either single or multi-tone injections. Moreover, we show to maximize lock range, the duty cycle of injection signals needs to be 50%. Finally, we show the phase noise of relaxation oscillators has a similar profile as that of harmonic oscillators. The quality factor of relaxation oscillators is smaller as compared with that of harmonic oscillators. The higher the degree of the nonlinearity of the relaxation oscillator, the smaller the quality factor of the relaxation oscillator subsequently the higher the phase noise. The theoretical findings on the lock range of relaxation oscillators are validated using the simulation results of a dual-comparator relaxation oscillator designed in TSMC 180 nm 1.8 V CMOS technology. [ABSTRACT FROM AUTHOR]

This paper presents a 1.05 MHz, on-chip RC relaxation oscillator (ROSC) with a temperature coefficient (TC) of 2.5 ppm/°C and an absolute variation of 100 ppm over the body-compatible range of 0–40°C. The TC increases to 4.3 ppm/°C over the range from −15 °C to 55 °C. The high temperature stability is achieved using a PTAT current reference and a TC-tunable resistor bank for first-order frequency error compensation along with a digital frequency compensation (DFC) block using a single-bit temperature sensor for second-order compensation. A measured RMS period jitter of 160 ps is achieved with a high-speed comparator. The active power consumption of the ROSC is $69~\mu \text{W}$ with a 1-V supply, and the leakage power consumption is 110 nW, while power gated. The ROSC achieves a fast startup time of $8~\mu \text{s}$ by employing a voltage buffer to quickly stabilize the voltage reference. [ABSTRACT FROM AUTHOR]

This paper presents a readout IC that uses an asynchronous capacitance-to-digital-converter (CDC) to digitize the capacitance of a touch sensor. A power-efficient tracking algorithm ensures that the CDC consumes negligible power consumption in the absence of touch events. To facilitate its use in wake-on-touch applications, the CDC can be periodically triggered by a co-integrated ultra-low-power relaxation oscillator. At a 38-Hz scan rate, the readout IC consumes 15 nW per touch sensor, which is the lowest reported to date. [ABSTRACT FROM AUTHOR]

A low-phase-noise relaxation oscillator uses a digital compensation loop to reduce its temperature coefficient (TC). This relaxation oscillator is fabricated in the 0.18- $\mu \text{m}$ CMOS process. The measured average oscillation frequency is 13.4 MHz. The whole oscillator consumes $157.8~\mu \text{W}$ under a 1.2-V supply. The measured average TCs of the oscillation frequency with and without compensation are 193.15 and 1098.7 ppm/°C, respectively. The TC achieves an improvement of 5.7 times. The measured frequency variation is within ±2% from −20 °C to 100 °C by using the digital compensation loop. The measured phase noise at 100-kHz offset frequency is −104.82 dBc/Hz, and the measured figure of merit (FOM) is −154.4 dBc/Hz. [ABSTRACT FROM AUTHOR]

This paper presents a power management unit (PMU) powered by a 1 mm $^{\boldsymbol{2}}$ solar cell on the same substrate to rise up the harvested voltage above 1.1 V. The on-chip solar cell and the PMU are fabricated in standard 0.18  $\mu$ m CMOS technology achieving a form factor of 1.575 mm $^{\boldsymbol{2}}$. The PMU is able to startup from a harvested power of 2.38 nW without any external kick off or control signal. The PMU features a continuous and two-dimensional maximum power point tracking (MPPT) working in open-loop mode to handle a harvested power range from nW to $\mu$ W, by modifying both the charge pump topology and the switching frequency. The MPPT is based on four voltage level detectors that define five working regions depending on the illumination and on a self-tuning reference current for a fine adjustment of the switching frequency. The chip also includes an auxiliary charge pump to generate the voltage level necessary for the control circuit, implemented as a Pelliconi charge pump of eight stages with NMOS transistors in P-well as diodes. A Dickson charge pump with transmission gates as switches and with variable gain and capacitance per stage is also designed as the main charge pump. Finally, two relaxation oscillators are implemented to drive both charge pumps. This paper is accompanied by a video file demonstrating the PMU operation by powering an off-chip nor gate. [ABSTRACT FROM AUTHOR]

This paper presents a simple, novel interfacing scheme for linear variable differential transformer (LVDT) that does not require a precise sine wave oscillator (with stable amplitude and frequency) for excitation or any phase matching circuit like traditional methods. The primary and the secondary coils of the LVDT are integral parts of a relaxation oscillator (RO). The RO injects a current waveform with a triangular shape through the primary coil which in turn induces a square-shaped voltage waveform in the secondary coils. The RO utilizes the amplitudes of those waveforms and generates a pulsewidth modulation (PWM) output signal whose duty cycle ratio is proportional to the measurand, core position. This quasi-digital PWM signal is passed through a low-pass filter to obtain an analog output. PWM time period measurement using a counter yields a digital output. This method guarantees good stability since the output is dependent only on a pair of dc reference voltages apart from the transformation constant of the sensor. A detailed analysis of the sources of error, their effect on the performance of the scheme and appropriate design choices for error mitigation are also presented. A prototype of the proposed circuit was built and tested in the laboratory. The nonlinearity error noted from the tests conducted was less than 0.16% for the analog output and 0.18% for the digital output. A resolution of up to 11 bits was achieved for the digital output. [ABSTRACT FROM AUTHOR]

In this paper, a pW-power relaxation oscillator for sensor node applications is presented. The proposed oscillator operates over a wide supply voltage range from nominal down to deep sub-threshold and requires only a sub-pF capacitor for Hz-range output frequency. A true pW-power operation is enabled thanks to the adoption of an architecture leveraging transistor operation in super-cutoff, the elimination of voltage regulation, and current reference. Indeed, the oscillator can be powered directly from highly variable voltage sources (e.g., harvesters and batteries over their whole charge/discharge cycle). This is achieved thanks to the wide supply voltage range, the low voltage sensitivity of the output frequency and the current drawn from the supply. A test chip of the proposed oscillator in 180 nm exhibits a nominal frequency of approximately 4 Hz, a supply voltage range from 1.8 V down to 0.3 V with 10%/V supply sensitivity, 8–18-pA current absorption, and 4%/°C thermal drift from -20 °C to 40 °C at an area of $1600~\mu \mathrm {m}^{2}$. To the best of the authors’ knowledge, the proposed oscillator is the only one able to operate from sub-threshold to nominal voltage. [ABSTRACT FROM AUTHOR]

A quadrature clock corrector uses relaxation oscillators to detect duty-cycle and quadrature phase errors by transforming them into pairs of frequencies, which are then digitized and compared. It achieves good detection accuracy and can detect a wide range of duty-cycle and quadrature phase errors. The prototype is implemented in a 55-nm CMOS process with a supply voltage of 1.2 V and occupies an area of 0.003 mm2. The experimental results show that the operation range is from 1 to 3 GHz, the power efficiency is 0.79 mW/GHz, the maximum duty-cycle error is 0.8% at 3 GHz, and the maximum quadrature phase error is 1.1° at 3 GHz. [ABSTRACT FROM AUTHOR]

In this brief, a relaxation oscillator with comparator delay compensation is presented. Two digital compensation loops are introduced to compensate for the comparator delay. This relaxation oscillator is fabricated in the 0.18- $\mu \text{m}$ CMOS process. The measured average oscillation frequency is 943.1 kHz. The whole oscillator consumes $5.2~\mu \text{W}$ under a 0.9-V supply. The measured average temperature coefficients (TCs) of the oscillation frequency with and without compensation are 93.88 and 618.17 ppm/°C, respectively. It achieves a TC improvement of $6.6\times $. The measured frequency variation is within ±0.7% from −10 °C to 100 °C by using the DCLs. The measured line sensitivity is 4.37%/V. The measured figure of merit (FOM2) is 173.3 dB. [ABSTRACT FROM AUTHOR]

A low-power relaxation oscillator with a high frequency stability is presented for radio frequency identification (RFID). This oscillator implements an improved self-biased and a comparator multiplexing techniques to reduce the power consumption and chip area. A capacitor resetting delay cancellation technique based on a two-phase operation and a proportional to absolute temperature (PTAT) current with an upward curvature versus the temperature are adopted to maintain the frequency stability. The oscillator is designed in a 65 nm standard CMOS process and occupies a small area of 0.0216 mm2. The post-layout simulation results show that a frequency drift of 0.95% from 0.7 to 1.7 V and a temperature stability of 27 ppm/°C as the temperature varies from − 40 to 85 °C at a typical working frequency of 1.92 MHz. Under a supply voltage of 0.7 V, the maximum power consumption is only 15.4 μW at − 40 °C. At room temperature, the figure of merit (FOM1 and FOM2) are 8 nW/kHz and 89.5 dB, respectively, which makes it more efficient than relaxation oscillators reported to date. [ABSTRACT FROM AUTHOR]

This paper presents a fully integrated, 8.2-MHz relaxation oscillator with a self-threshold-tracking loop and swing-boosting technique for improving its long-term frequency stability and noise performance. The proposed latch-based relaxation oscillator increases the transition speed to reduce the static power consumption. To decrease the process–voltage–temperature dependence, we propose a self-threshold-tracking loop to ensure that the transition point of the inverter-based comparator is set to a fixed ratio of the supply voltage. In addition, the comparator delay can be compensated by the tracking loop, relaxing the requirements of comparator power consumption. The design is implemented in a 0.18- $\mu \text{m}$ CMOS process. The design achieves a period jitter of 7.66 psrms, the phase noise of −109 dBc/Hz at an offset frequency of 100 kHz, and an Allan deviation noise floor of 1.56 ppm. The resultant figure of merit is 160.8 dBc/Hz, while only consuming 46.3 $\mu \text{W}$. The power efficiency of the design is 5.6 kHz/nW. As for the supply sensitivity, the design achieves 0.9 %/0.1 V, which is 10 $\times $ lower than the design with no compensation loop. The measured temperature coefficient of the proposed oscillators is 123 ppm/°C from −20 °C to 100 °C without any trimming process. [ABSTRACT FROM AUTHOR]

Oscillatory rhythms are investigated in a model network where a pair of excitatory neurons interact via an inhibitory neuron. Each individual neuron is modeled as a relaxation oscillator, and a slow/fast decomposition process reduces the problem of a stable oscillatory rhythm to the problem of a stable fixed point of a map. Further reduction of the map is made by finding an invariant manifold. A detailed analysis of the reduced map reveals how different types of stable oscillatory rhythms arise, depending on the intrinsic properties of the individual neurons and the synaptic time constant. [ABSTRACT FROM AUTHOR]

A method of generating a non-zero frequency spacing between two laser diodes, using four-wave mixing, mediated by injection-locking in order to potentially realise THz radiation is presented. Four distinct regimes of operation are observed, including a periodic response, where the oscillations are simply related to the relaxation oscillations of the system; a periodic response with multiple frequency components, where there is a harmonic relationship between the fundamental frequency and the other frequency components; a chaotic response, where the apparent frequency components are not harmonically related; and finally the locking condition between the lasers, where a continuous wave operation is apparent. A clear linear relationship between the frequency offset and the detuning frequency while operating under the locking condition is observed, and there is a clear transition in behaviour on either side of the locking region, where the system shows a nonlinear behaviour. For higher injection rates, locking is only observed at either end of the locking region, and from this arises a so-called generalised locking region. [ABSTRACT FROM AUTHOR]

In this paper, we prove the existence and uniqueness of relaxation oscillation cycle of a slow–fast modified Leslie–Gower model via the entry–exit function and geometric singular perturbation theory. Numerical simulations are also carried out to illustrate our theoretical result. [ABSTRACT FROM AUTHOR]

Abstract The discontinuity mapping technique provides quite a good way to study the near-grazing dynamics in the impacting oscillators. However, disagreements between the results obtained by the discontinuity mapping technique and the direct numerical observations still exist in terms of modeling and stability analysis. In particular, when applying the existing theory to deal with the complicated degenerate or other co-dimension two grazing bifurcations, even potential mistake in the qualitative analysis might arise. To reduce such disagreements, the local zero time discontinuity mapping is extended to higher order terms for the generic multi-degree-of-freedom impacting oscillators under harmonic excitation in this paper. Furthermore, to demonstrate the necessity and feasibility of using the higher order zero time discontinuity mapping for the analysis of degenerate grazing bifurcation, comparisons between the lower and higher order truncation are made through the existence analysis of near-grazing impact periodic motions. Highlights • The existing local zero time discontinuity mapping is extended to higher order terms. • Comparisons between the lower and higher order truncation are presented. • The necessity of higher order discontinuity mapping for degenerate grazing is shown. [ABSTRACT FROM AUTHOR]

Abstract Retriggerable and non-retriggerable monostable multivibrators are simple timers with a single characteristic, their period. Motivated by the fact that monostable multivibrators are implementable in large quantities as counters in digital programmable hardware, we set out to investigate their applicability as building blocks of artificial neural networks. We derive the nonlinear input–output firing rate relations for single multivibrator neurons as well as the equilibrium firing rate of large recurrent networks. We show that in rate-encoded monostable multivibrators networks the synaptic weights are tunable as the period ratio of connected units, and thus reconfigurable at run time in a counter-based digital implementation. This is illustrated with the task of handwritten digit recognition. Furthermore, we show in a task-independent manner that networks of monostable multivibrators are capable of nonlinear separation, when operating directly on pulse streams. Our research implies that pulse-coupled neural networks with excitable neurons showing a delayed response can perform computations even when working solely with suprathreshold pulses. [ABSTRACT FROM AUTHOR]

In this paper, we propose a fully integrated and area‐efficient resistor‐less relaxation oscillator (ROSC) for ultra‐low power real‐time clock (RTC) applications. The proposed ROSC is based on a conventional current‐mode ROSC and is modified to be an area‐efficient circuit configuration without using resistors. The proposed ROSC consists of a temperature‐compensated bias current generator (BCG), proportional to absolute temperature (PTAT) voltage source, current‐mode ROSC, shunt regulator, and output logic circuit. The BCG, PTAT voltage source, and shunt regulator are used to compensate for the temperature characteristics of the ROSC. The area of our proposed ROSC was extremely small, 0.022 mm2. Simulated results demonstrated that our proposed ROSC generates a 32.5 kHz clock frequency and achieves ultra‐low power dissipation of 271 nW. The temperature and voltage dependence of the oscillation frequency were 138 ppm/°C and 13.9 ppm/mV, respectively. Monte Carlo statistical simulations showed that the mean, standard deviation, and coefficient of variation are 32.3, 0.6 kHz, and 1.9%, respectively. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

We propose a resonant tunneling diode (RTD)-based relaxation oscillator and an oscillator-based terahertz (THz) wireless link that compensate for shortfalls in RF-oscillator emission power by adding several relaxation carrier wave harmonic modes. We believe that the proposed link can perform as well as or superior to large component-based wireless links that suppress power dissipation using collimating lenses and/or discrete antennas to add the power output of a relaxation oscillator. This hypothesis is investigated analytically using a physics-based equivalent circuit model of the proposed oscillator and a link budget analysis of the relaxation carrier wave. The model, which incorporates effects such as the non-linearity of the tunneling diode and the electromagnetic properties of the integrated bow-tie antenna on the oscillator, is used to quantitatively investigate the link characteristics in terms of the signal-to-noise ratio (SNR) and other parameters and to demonstrate that, by applying an appropriate device size and number of harmonic modes in the occupied bandwidth, link performance comparable to that of previously reported wireless links can be achieved. Based on these results, we discuss the potential for practical implementation of the proposed link configuration in mobile link applications for use in environments such as the Internet of Things (IoT). [ABSTRACT FROM AUTHOR]

Presents information on a study which demonstrated that the relaxation oscillation resonance and the resonance in the wavelength chirp can be eliminated by an axially nonuniform photon density. Mechanism that causes the reduction in the resonance due to the result of an antireflective coating; Effect of the microwave power on the optical spectrum; Conclusions.

Discusses the use of double relaxation oscillation superconducting quantum interference devices with a gradiometric layout. Devices with a reference junction; Operation in a flux locked loop based on direct voltage readout without loss of sensitivity; Measurement of a white magnetic field sensitivity inside a magnetically shielded room.

Reports on a study which characterized the relaxation oscillation superconducting (ROS) quantum interference devices (SQUID) and double relaxation oscillation SQUID. Theory of operation of a ROS; Numerical simulation of ROS operation range; Conclusions.

Neuromorphic computing using neural network hardware has attracted significant interest as it promises improved performance at low power for data-intensive error-resilient graphical signal processing. Oscillatory neural networks (ONNs) use either frequency or phase as state variables to implement frequency-shift keying (FSK)- and phase-shift keying (PSK)-based neural networks, respectively. To make these ONNs power and area efficient, back-end-of-the-line compatible, and capable of processing multilevel information, we explore an emerging class of oscillators that show fine-grain frequency-tuning and phase-coupling. We examine TaOx- and TiOx-based oscillators (resistive random access memory-type) as elements of a neuromorphic compute block and experimentally demonstrate: 1) frequency control over four decades using a ballast MOSFET; 2) variable phase coupling between oscillators; and 3) variable phase programming between oscillators coupled with a MOSFET. Such fine-grain control over both frequency and relative phase serve as the desirable characteristics of oscillators required for multilevel information processing in star-type directly coupled FSK- and PSK-based neuromorphic systems that find applications in gray-scale image processing and other graphical compute paradigms. These attributes combined with the small size (2) and simplicity, make these devices attractive candidates for realizing large-scale neuromorphic systems at reasonable size and power.

Robust output tracking control of Van der Pol oscillator is an important practical problem from an application point of view. Output feedback‐based robust tracking control strategies are proposed in this work for that purpose. First, a high‐order sliding‐mode observer is used to estimate the oscillator states from the measurable output and to identify some types of disturbances. Then, five different continuous sliding‐modes controllers (Continuous‐SMCs) are provided to robustly track a desired time‐varying trajectory, exponentially or in a finite time, for the Van der Pol oscillator despite the presence of external disturbances. The closed‐loop stability for each Continuous‐SMC is given based on input‐to‐state stability properties. Finally, experimental validations are also provided to show the feasibility of the proposed controllers in real time. [ABSTRACT FROM AUTHOR]

Fenichel’s geometric singular perturbation theory and the blow-up method have been very successful in describing and explaining global non-linear phenomena in systems with multiple time-scales, such as relaxation oscillations and canards. Recently, the blow-up method has been extended to systems with flat, unbounded slow manifolds that lose normal hyperbolicity at infinity. Here, we show that transition between discrete and periodic movement captured by the Jirsa-Kelso excitator is a new example of such phenomena. We, first, derive equations of the Jirsa-Kelso excitator with explicit time scale separation and demonstrate existence of canards in the systems. Then, we combine the slow-fast analysis, blow-up method and projection onto the Poincaré sphere to understand the return mechanism of the periodic orbits in the singular case, ϵ = 0. [ABSTRACT FROM AUTHOR]

The existence of limit cycles ensures that the dynamic systems generate a rhythmic oscillation phenomenon. In this paper, the investigation of limit cycles in the fractional-order Relaxation oscillator was demonstrated by analysis of the stability domains, and the simulation of the cortex rhythms was implemented based on the fractional-order Relaxation model. When the fractional-order Relaxation oscillator oscillates in rhythm, the Quasi Gamma Curve (QGC) Model was established. The proposed QGC Model was applied to enhance images. The performance of image enhancement based on QGC model was improved compared with the Gamma correction curve and the Retinex algorithm. [ABSTRACT FROM AUTHOR]

Summary: Recently, memristive oscillators are a significant topic in the nonlinear circuit theory where there is a possibility to build relaxation oscillators without existence of reactive elements. In this paper, a family of voltage‐controlled memristor‐based relaxation oscillator including two memristors is presented. The operation of two memristors‐based voltage relaxation oscillator circuits is demonstrated theoretically with the mathematical analysis and with numerical simulations. The generalized expressions for the oscillation frequency and conditions are derived for different cases, where a closed form is introduced for each case. The effect of changing the circuit parameters on the oscillation frequency and conditions is investigated numerically. In addition, the derived equations are verified using several transient PSPICE simulations. The power consumption of each oscillator is obtained numerically and compared with its PSPICE counterpart. Furthermore, controlling the memristive oscillator with a voltage grants the design an extra degree of freedom which increases the design flexibility. The nonlinear exponential model of memristor is employed to prove the oscillation concept. As an application, two examples of voltage‐controlled memristor‐based relaxation oscillator are provided to elaborate the effect of the reference voltage on the output voltage. This voltage‐controlled memristor‐based relaxation oscillator has nano size with storage property that makes it more efficient compared with the conventional one. It would be helpful in many communication applications. [ABSTRACT FROM AUTHOR]

p53 network, which is responsible for DNA damage response of cells, exhibits three distinct qualitative behaviours; low state, oscillation and high state, which are associated with normal cell cycle progression, cell cycle arrest and apoptosis, respectively. The experimental studies demonstrate that these dynamics of p53 are due to the ATM and Wip1 interaction. This paper proposes a simple two-dimensional canonical relaxation oscillator model based on the identified topological structure of ATM and Wip1 interaction underlying these qualitative behaviours of p53 network. The model includes only polynomial terms that have the interpretability of known ATM and Wip1 interaction. The introduced model is useful for understanding relaxation oscillations in gene regulatory networks. Through mathematical analysis, we investigate the roles of ATM and Wip1 in forming of these three essential behaviours, and show that ATM and Wip1 constitute the core mechanism of p53 dynamics. In agreement with biological findings, we show that Wip1 degradation term is a highly sensitive parameter, possibly related to mutations. By perturbing the corresponding parameters, our model characterizes some mutations such as ATM deficiency and Wip1 overexpression. Finally, we provide intervention strategies considering our observation that Wip1 seems to be an important target to conduct therapies for these mutations. [ABSTRACT FROM AUTHOR]

Applications of generalized linear multiplicative programming problems (LMP) can be frequently found in various areas of engineering practice and management science. In this paper, we present a simple global optimization algorithm for solving linear multiplicative programming problem (LMP). The algorithm is developed by a fusion of a new convex relaxation method and the branch and bound scheme with some accelerating techniques. Global convergence and optimality of the algorithm are also presented and extensive computational results are reported on a wide range of problems from recent literature and GLOBALLib. Numerical experiments show that the proposed algorithm with a new convex relaxation method is more efficient than usual branch and bound algorithm that used linear relaxation for solving the LMP. [ABSTRACT FROM AUTHOR]

The asynchronous communication always exists in networked control systems that consist of interconnected heterogeneous subsystems. To improve the closed‐loop performance, a networked and distributed predictive controller is developed for such a system in this study. At each time instant, a virtual trajectory generator for the interconnected agents with guaranteed error bounds is proposed to implement the receding horizon optimisation. Then, a dual‐mode strategy is designed for the asynchronous distributed model predictive control to make effective use of computational resources. Conditions for ensuring the feasibility of the proposed algorithm and the stabilisation of the closed‐loop networked control systems are developed, respectively. Finally, a simulation example of a set of coupled Van der Pol oscillators is presented to illustrate the results. [ABSTRACT FROM AUTHOR]

This letter presents a charge-transfer relaxation oscillator that achieves ultra-low power operation without comparator. The oscillator is implemented by charging or discharging the negative plate of the capacitor to a reference voltage through charge-transfer technique and the positive plate of the capacitor by a constant reference current, respectively. A special sawtooth waveform is generated, and a pseudo-inverter chain with delay compensation is adopted to determine the oscillation state. In the proposed structure, a conventional comparator has been eliminated to avoid comparator offset effect. The oscillator has been implemented with TSMC 0.18 μm CMOS process. The circuit operates in subthreshold region and consumes a total power of 85 nW. The circuit demonstrates a frequency variation less than 0.8%/V over 1.2-1.8 V, leading to a temperature coefficient of 33 ppm/∘C over − 40 to 80 ∘C. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride (PVC) is widely used as insulator in electrical engineering especially as cable insulation sheaths. In order to improve the dielectric properties, polymers are mixed with ceramics. In this paper, PVC composites with different weight percentages 2 wt.%, 5 wt.%, 8 wt.% and 10 wt.% were prepared and investigated. Loss index () and dielectric constant () have been measured using an impedance analyzer RLC. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) have been used as characterization techniques. The incorporation of BaTiO3 does not modify the crystallinity and the morphology of the PVC but reduces the space charges, therefore the dielectric losses. The frequency response analysis has been followed in the frequency ranges (20-140 Hz and 115-1 MHz). Relaxation frequencies have been evaluated in each frequency range. Experimental measurements have been validated using Cole-Cole's model. Experimental results show well that BaTiO3 as a filler improves the dielectric properties of PVC. [ABSTRACT FROM AUTHOR]

Dynamics of a homogeneous neural population interacting with active extracellular mediumwere considered. The correspondingmathematicalmodel was tuned specifically to describe the behavior of interneurons with tonic GABA conductance under the action of non-stationary ambient GABA. The feedback provided by the GABA mediated transmembrane current enriched the repertoire of population activity by enabling the oscillatory behavior. This behavior appeared in the form of relaxation oscillations which can be considered as a specific type of brainwaves. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF), an effective mechanism to break the 25% statistic limit of organic light-emitting diodes (OLEDs) internal quantum efficiency, has become an active topic recently. The key to germinate TADF is the achievement of efficient reverse intersystem crossing from triplet spin state to singlet state by thermal activation, which is obviously a temperature dependence process. The direct way of thermal activation is the absorption of phonon energy, in which the transition rate from triplet state to singlet state has the Boltzmann distribution function dependence of the temperature. Nevertheless, the molecular vibration could engender spin relaxation of excitons, giving rise to different temperature dependence. This could be regarded as an indirect way of thermal activation. Here, we investigate the effect of spin relaxation caused by molecular vibration on TADF and analyze the change principles of the efficiency of TADF processes versus temperature. It is found that the experimental dependence could be well explained when the spin relaxation induced by molecular vibration is considered. Therefore, the consideration of this process helps us to understand TADF more comprehensively. [ABSTRACT FROM AUTHOR]

Block copolymer directed self-assembly (DSA) is a simple and promising candidate next-generation device fabrication technology, which is low-cost as complement with multi-patterning for contact layer patterning. In this paper, we consider the contact layer mask and template assignment problem of DSA with triple patterning lithography of general layout. To address this problem, first we construct a weighted conflict grouping graph, in which edges with negative weights are introduced, then a discrete relaxation based mask assignment problem is proposed. The integer linear program (ILP) formulation of the discrete relaxation problem is solved for obtaining a lower bound on the optimal value of this problem. In order to improve the lower bound, some valid inequalities are introduced to prune some poor relaxation solutions. At last, the obtained discrete relaxation solution is transformed to a legal solution of the original problem by solving a template assignment problem on the layout graph, which provides an upper bound on the optimal value of the original problem. Experimental results and comparisons show the effectiveness and efficiency of our method. In addition, under the discrete relaxation theory, the quality of our experimental results can be evaluated by the obtained upper and lower bounds. Specifically, the gap between the obtained upper and lower bounds is 0 for most of the sparse benchmarks, and the average gap is 0.4% for dense benchmarks. [ABSTRACT FROM AUTHOR]

We present a theoretical and experimental study of a low-frequency optoelectronic oscillator featuring both laserdiode and Van der Pol-like nonlinearities. In this architecture, the device performing the electrical-to-optical conversion is the laserdiode itself instead of an external electro-optical modulator, while the electric branch of the oscillator is characterized by a Van der Pol nonlinear transfer function.We show that the system displays a complex autonomous dynamics, induced by the competition between these two nonlinearities. In the case of small delay, the system displays harmonic and relaxation oscillations. When the delay is large, the interplay between the two nonlinearities leads to a period-doubling route of bifurcations as the feedback gain is increased, and ultimately to fully developed chaos. Our experimental measurements are in good agreement with the theoretical analysis. [ABSTRACT FROM AUTHOR]

This study investigates the temperature dependence of current-controlled negative differential resistance (CC-NDR) in Pt/NbOx/TiN devices and its effect on the dynamics of associated Pearson-Anson relaxation oscillators. The voltage range over which CC-NDR is observed decreases with increasing temperature such that no NDR is observed for temperatures above ~380K. Up to this temperature, relaxation oscillators exhibit voltage and temperature dependent oscillation frequencies in the range of 1 to 13MHz. Significantly, the sensitivity of the frequency to temperature changes was found to be voltage-dependent, ranging from 39.6 kHz/K at a source voltage of 2V to 110 kHz/K at a source voltage of 3V, in the temperature range of 296–328K. Such a behaviour provides insights into temperature tolerance and tuning variability for environmentally sensitive neuromorphic computing. [ABSTRACT FROM AUTHOR]

This letter presents a new pseudo-random pattern generator using a memristor and relaxation oscillator based on an operational amplifier. The pulse width of the proposed generator is determined by the resistance storage property of the memristor, and the random pulse sequence depends on the RC time constant of the relaxation oscillator. From the simulation results, we show that the pulse width time is 7.6 μs, and the random pulse sequence is 2048 bits. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

An out-of-plane capacitive accelerometer with low cross axis sensitivity at high accelerations based on a CMOS MEMS process is developed. A truss frame with a high ratio of in-plane stiffness to out-of-plane stiffness is designed to suspend the proof mass of the accelerometer. The configuration of the proof mass with four auxiliary masses surrounding a main mass boosts the sensitivity of the accelerometer in the out-of-plane direction. A sensing circuit with period modulated output signals is realized by applying a relaxation oscillator to the sensing capacitors. The relaxation oscillator converts the capacitance changes to frequency variations. Analytical models are developed to assist the design of the accelerometer. The nonlinearity and sensitivity of the accelerometer are 1.1% and 754 Hz/g, respectively, for the acceleration ranging from 0 to 9 g. Measured cross-axis sensitivity is 4% at an acceleration of 9 g. The power consumption is 1.7 mW under a 1.8 V supply. [Display omitted] • A single axis accelerometer with low cross-axis sensitivity was developed. • Employ a truss with high in-plane stiffness and low out-of-plane stiffness. • Readout circuit based on acceleration to frequency converter. [ABSTRACT FROM AUTHOR]

Spin torque nano-oscillators are nanoscopic microwave frequency generators which excel due to their large frequency tuning range and agility for amplitude and frequency modulation. Due to their compactness, they are regarded as suitable candidates for applications in wireless communications, where cost-effective and complementary metal-oxide semiconductor-compatible standalone devices are required. In this work, we study the ability of a magnetic-tunnel-junction based spin torque nano-oscillator to respond to a binary input sequence encoded in a square-shaped current pulse for its application as a frequency-shift-keying (FSK) based emitter. We demonstrate that below the limit imposed by the spin torque nano-oscillator intrinsic relaxation frequency, an agile variation between discrete oscillator states is possible. For this kind of devices, we demonstrate FSK up to data rates of 400 Mbps, which is well suited for the application of such oscillators in wireless networks. [ABSTRACT FROM AUTHOR]

We give a geometric analysis of relaxation oscillations and canard cycles in a singularly perturbed predator–prey system of Holling and Leslie types. We discuss how the canard cycles are found near the Hopf bifurcation points. The transition from small Hopf-type cycles to large relaxation cycles is also discussed. Moreover, we outline one possibility for the global dynamics. Numerical simulations are also carried out to verify the theoretical results. [ABSTRACT FROM AUTHOR]

Vibrational band shape analysis through time correlation function concept is widely used to obtain experimental information on the molecular dynamics of medium-size molecules in different environments. Interesting details are revealed by extending this technique to biomolecules such as functional groups of the nucleic acids in media approaching the physiological conditions. In this work a study into the UV resonance Raman (UVRR) vibrational half bandwidths of functional groups in LacDNA, upon lowering the pH (pH 6.4, pH 3.45) and in the presence of Mn2+ and Ca2+ ions, respectively, was of interest. The corresponding global relaxation times have been derived. Also, the 793 cm-1 UVRR band, corresponding to ν (backbone O-P-O, dT) oscillator of LacDNA in aqueous solutions, was selected for band shape-analysis. Vibrational relaxation appears as the dominant relaxation process for this mode, with vibrational dephasing being the most efficient for this oscillator. Current theories developed for vibrational dephasing have been applied to this profile, and relevant relaxation parameters have been obtained and discussed. To our knowledge this is the first study on DNA oligomers vibrational band shape analysis through time correlation function concept. [ABSTRACT FROM AUTHOR]

A novel readout circuit for interfacing single element resistive sensors is presented in this paper. The proposed scheme is based on a new relaxation oscillator (RO). The RO, along with a timer counter provides a digital output proportional to the resistance of the sensor. The output characteristic of most of the existing readout circuits for resistive sensors suffers from gain, offset, and nonlinearity errors. The sources of errors include various nonideal circuit parameters and their drift. The output of the proposed readout circuit has a special feature that it is not a function of the circuit parameters such as: 1) offset voltages of the opamps and comparators; 2) bias currents of the opamps and comparators; 3) gain of various units employed; 4) ON-resistance of the switches; 5) value or mismatch in the magnitudes of the reference voltages employed; 6) delay of the switches and comparator; 7) leakage current of the switch; and 8) slew rate of the opamp. Such a scheme will be useful for high accuracy measurements, even when the parameters 1)–8) may vary or drift, due to variation in the measurement environment. A prototype of the proposed readout scheme has been developed in the laboratory and the performance has been evaluated under various conditions. The output was found to be linear with a worst-case nonlinearity of 0.05%. Test results from a prototype developed show that the proposed scheme possesses all the features, described above, as expected. [ABSTRACT FROM PUBLISHER]

A complementary metal oxide semiconductor relaxation oscillator adopting a new frequency self-calibration technique (FSCT) to improve the linearity is proposed in this paper. The FSCT can detect the peak voltage of the timing capacitor when start-up and change the reference voltage adaptively. Then, the non-linearity of the oscillator caused by the delay of the control circuit and the offset voltage of the comparator can be reduced obviously. The proposed relaxation oscillator with typical frequency of 5 MHz is implemented in 0.5 μm Silicon-On-Insulator Bipolar-CMOS-DMOS process. Measured results show that <0.79% non-linearity in the current-frequency transfer function from 0.1 to 10 MHz without trimming. [ABSTRACT FROM AUTHOR]