Glitch Generator Research Articles

One flexible model for multiclass gravitational wave signal and glitch generation

One flexible model for multiclass gravitational wave signal and glitch generation

The stability of core-envelope models for the Crab and the Vela pulsars

The core–envelope analytic models of Negi et al. (Class. Quantum Gravity 6:1141, 1989) have been found to be consistent with both the mechanisms of glitch generation in pulsars, namely (i) the starquake model and (ii) the vortex unpinning model. In Negi (Astrophys. Space Sci. 364:149, 2019, arXiv:2105.14324), the author has been able to reproduce the observed values of the glitch healing parameter, \(G_{h}\) (\(= I_{\mathrm{core}}/I_{\mathrm{total}}\); \(G_{h}\) represents the fractional moment of inertia of the core component in the starquake mechanism of glitch generation) for the Crab as well as for the Vela pulsar. In another study, by using the models discussed in Negi et al. (Class. Quantum Gravity 6:1141, 1989), the author has obtained the minimum value of fractional moment of inertia of the crust about 7.4% and larger for all the values of masses in the range \(1M_{\odot }\)–\(1.96M_{\odot }\) considered for the Vela pulsar (Negi in J. Eng. Sci. 11:86, 2020a, arXiv:2106.02439). The latter study of the author is found to be consistent with the recent requirement (on the basis of vortex unpinning model of the glitch generation) which reveals that the minimum fractional crustal moment of inertia of the Vela pulsar should be about 7% for a mass higher than about 1\(M_{\odot }\). However, a thorough study which requires investigation of pulsational stability and gravitational binding of the models of Negi et al. (Class. Quantum Gravity 6:1141, 1989) has not been carried out so far. The present paper deals with such a study of the models (Negi et al. in Class. Quantum Gravity 6:1141, 1989) for all permissible values of the compactness parameter \(u\) (\(\equiv M/a\), the total mass to size ratio in geometrized units) and compressibility factor \(Q\) (defined in Tolman’s VII solution as \(x = r^{2}/K^{2} = r^{2}/a^{2}Q\)). It is seen that the configurations remain pulsationally stable and gravitationally bound for all permissible values of \(u\) \((\leq 0.25)\) and \(Q\) (\(0 < Q \leq 1.2\)).

Clock glitch fault injection attack on an FPGA-based non-autonomous chaotic oscillator

Chaos-based true random bit generators have been demonstrated in many studies to be feasible and secure for crypto-system applications. In this work, we demonstrate that an FPGA-based non-autonomous chaotic oscillator, used as a true random number generator, can be compromised via cryptanalysis attacks. First, we realize non-autonomous chaotic oscillator (previously implemented only in analog form) on a modular FPGA platform. The oscillator architecture is simplified to eliminate the Sin function and is described in details in VHDL. Then, we propose chaotic oscillator attacking system including clock glitch generator to compromise the oscillator by injecting glitches on function clock. The parameters and positions of those glitches are carefully determined to achieve a successful attack. The experimental results show that the system is attacked, and the generated glitched bit-streams are distorted, unlike the bit-streams generated without glitching. The randomness of the generated bit-streams is checked using the NIST test tool.

Enhancing Tumor Detection in IR-UWB Breast Cancer System.

An ultra-wideband (UWB) microwave system for breast cancer detection is presented. The proposed system includes monocycle pulse generator, antipodal Vivaldi antenna, breast model, and calibration algorithm for tumor detection. Firstly, our pulse generator employs transmission gate in glitch generator to achieve several advantages such as low power consumption and low ringing level. Secondly, the antipodal Vivaldi antenna is designed assuming FR4 dielectric substrate material, and developed antenna element (80 × 80 mm2) features a −10 dB return loss and bandwidth ranges from 2.3 GHz to more than 11 GHz. Thirdly, the phantom breast can be modeled as a layer of skin, fat, and then tumor is inserted in this layer. Finally, subtract and add algorithm (SAD) is used as a calibration algorithm in tumor detection system. The proposed system suggested that horizontal antenna position with 90° between transmitting and receiving antennas is localized as a suitable antenna position with different rotating location and a 0.5 cm near to phantom. The mean advantages of this localization and tracking position around breast is a high received power signal approximately around mv as a higher recognized signal in tumor detection. Using our proposed system we can detect tumor in 5 mm diameter.

A ROM Driving Circuit for RFID Tags Based on a-IGZO TFTs

This paper proposes a read-only memory driving circuit for RFID tags based on a-IGZO thin-film transistors. The circuit consists of a Johnson counter and monotype complementary gates. By utilizing complementary signals to drive a decoder based on monotype complementary gates, the propagation delay can be decreased and the redundant current can be reduced. The Johnson counter reduces the number of registers. The new circuit can effectively avoid glitch generation, and reduce circuit power consumption and delay.

New design of low power, 100 Mb-s IR-UWB pulse generator in 0.18 µm CMOS technology

A new method of impulse radio ultra-wideband (IR-UWB) pulse generation, with advantage of providing a “notch” like representation of pulse in the spectrum domain for particular control parameters values, is investigated in this paper. Low power pulse generator is composed of a glitch generator, a switched oscillator, a two-stage buffer and a pulse shaping filter. The proposed architecture, designed in UMC 0.18µm CMOS technology, can operate in a single band from 3.3GHz to 9.3GHz or in a double, lower and higher UWB band (from 3GHz to 9.15GHz), suppressing frequencies in the WLAN band. Both spectrums fully comply with the corresponding FCC spectral mask, while the pulse generator regime and the spectrum range are determined by control signal values. Post-layout simulation results showed a pulse width of 0.5ns, and a peak-to-peak amplitude of 211mV for one band spectrum. The average power consumption is 0.89mW corresponding to the energy consumption of 8.9pJ/pulse for 100MHz pulse repetition rate (PRF). The pulse duration is 1ns and peak-to-peak amplitude is 202mV in the case of the WLAN frequency band suppression. The total chip area is 0.31mm2. The pulse generator has been evaluated for the best performance supporting the on-off keying (OOK) modulation.

A 5‐GHz energy‐efficient tunable pulse generator for ultra‐wideband applications using a variable attenuator for pulse shaping

SUMMARYA new energy‐efficient tunable pulse generator is presented in this paper using 0.13‐µm CMOS technology for short‐range high‐data‐rate 3.1–10.6 GHz ultra‐wideband applications. A ring oscillator consisting of current‐starved CMOS inverters is quickly switched on and off for the duration of the pulse, and the amplitude envelope is shaped with a variable passive CMOS attenuator. The variable passive attenuator is controlled using an impulse that is created by a low‐power glitch generator (CMOS NOR gate). The glitch generator combines the falling edge of the clock and its delayed inverse, allowing the duration of the impulse to be changed over a wide range (500–900 ps) by varying the delay between the edges. The pulses generated with this technique can provide a sharp frequency roll off with high out‐of‐band rejection to help meet the Federal Communications Commission mask. The entire circuit operates in switched mode with a low average power consumption of less than 3.8 mW at 910 MHz pulse repetition frequency or below 4.2 pJ of energy per pulse. It occupies a total area of 725 × 600 µm2 including bonding pads and decoupling capacitors, and the active circuit area is only 360 × 200 µm2. Copyright © 2011 John Wiley &amp; Sons, Ltd.

A Quadrature Pulse Generator for Short-Range UWB Vehicular Radar Applications Using a Pulsed Oscillator and a Variable Attenuator

A new quadrature tunable pulse generator is presented in this paper using 0.13 μm CMOS for 22-29 GHz ultrawideband (UWB) vehicular radar. A quadrature inductor-capacitor (LC) oscillator is quickly switched on and off for the duration of the pulse, and the amplitude envelope is modulated with an impulse using a variable passive CMOS attenuator. The impulse is realized using a glitch generator (CMOS nand gate) and its duration can be changed over a wide range (375 ps to more than 1 ns). The switching technique used in the quadrature oscillator creates a large initial voltage for fast startup (0.5 ns) and locks the initial phase of the oscillations to the input clock for pulse coherence. The measured phase noise thus matches that of the clock signal, with a relatively low phase noise of -70 dBc/Hz and -100 dBc/Hz at 1kHz and 1 MHz offsets respectively. The entire circuit operates in switched-mode with a low average power consumption of less than 2.2 mW and 14.8 mW at 50 MHz and 600 MHz pulse repetition frequencies, or below 11 pJ of energy for each of the four differential quadrature pulses. It occupies an active area of less than 0.41 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

A study of 315 glitches in the rotation of 102 pulsars

The rotation of more than 700 pulsars has been monitored using the 76-m Lovell Telescope at Jodrell Bank. Here we report on a new search for glitches in the observations, revealing 128 new glitches in the rotation of 63 pulsars. Combining these new data with those already published we present a database containing 315 glitches in 102 pulsars. The database was used to study the glitch activity among the pulsar population, finding that it peaks for pulsars with a characteristic age tau_c ~ 10kyr and decreases for longer values of tau_c, disappearing for objects with tau_c > 20Myr. The glitch activity is also smaller in the very young pulsars (tau_c <~ 1kyr). The cumulative effect of glitches, a collection of instantaneous spin up events, acts to reduce the regular long term spindown rate |nudot| of the star. The percentage of |nudot| reversed by glitch activity was found to vary between 0.5% and 1.6% for pulsars with spindown rates |nudot| between 10^(-14) and 3.2*10^(-11) Hz/s, decreasing to less than 0.01% at both higher and lower spindown rates. These ratios are interpreted in terms of the amount of superfluid involved in the generation of glitches. In this context the activity of the youngest pulsar studied, the Crab pulsar, may be explained by quake-like activity within the crust. Pulsars with low spindown rates seem to exhibit mostly small glitches, matching well the decrease of their crustal superfluid. Through the analysis of glitch sizes it was found that the particular glitching behaviour of PSR J0537-6910 and the Vela pulsar may be shared by most Vela-like pulsars. These objects present most of their glitches with characteristic frequency and frequency derivative jumps, occurring at regular intervals of time. Their behaviour is different from other glitching pulsars of similar characteristic age.

Neutron star sequences and the starquake glitch model for the Crab and the Vela pulsars

We construct for the first time, the sequences of stable neutron star (NS) models capable of explaining simultaneously, the glitch healing parameters, Q, of both the pulsars, the Crab (Q≥0.7) and the Vela (Q≤0.2), on the basis of starquake mechanism of glitch generation, whereas the conventional NS models cannot give such consistent explanation. Furthermore, our models also yield an upper bound on NS masses similar to those obtained in the literature for a variety of modern equations of state (EOSs) compatible with causality and dynamical stability. If the lower limit of the observational constraint of (i) Q≥0.7 for the Crab pulsar and (ii) the recent value of the moment of inertia for the Crab pulsar (evaluated on the basis of time-dependent acceleration model of the Crab Nebula), I Crab,45≥1.93 (where I 45=I/1045 g cm2), both are imposed together on our models, the models yield the value of matching density, E b =9.584×1014 g cm−3 at the core-envelope boundary. This value of matching density yields a model-independent upper bound on neutron star masses, M max≤2.22M ⊙, and the strong lower bounds on surface redshift z R ≃0.6232 and mass M≃2.11M ⊙ for the Crab (Q≃0.7) and the strong upper bound on surface redshift z R ≃0.2016, mass M≃0.982M ⊙ and the moment of inertia I Vela,45≃0.587 for the Vela (Q≃0.2) pulsar. However, for the observational constraint of the ‘central’ weighted mean value Q≈0.72, and I Crab,45>1.93, for the Crab pulsar, the minimum surface redshift and mass of the Crab pulsar are slightly increased to the values z R ≃0.655 and M≃2.149M ⊙ respectively, whereas corresponding to the ‘central’ weighted mean value Q≈0.12 for the Vela pulsar, the maximum surface redshift, mass and the moment of inertia for the Vela pulsar are slightly decreased to the values z R ≃0.1645, M≃0.828M ⊙ and I Vela,45≃0.459 respectively. These results set an upper and lower bound on the energy of a gravitationally redshifted electron-positron annihilation line in the range of about 0.309–0.315 MeV from the Crab and in the range of about 0.425–0.439 MeV from the Vela pulsar.

Soft error generation analysis in combinational logic circuits

Reliability is expected to become a big concern in future deep sub-micron integrated circuits design. Soft error rate (SER) of combinational logic is considered to be a great reliability problem. Previous SER analysis and models indicated that glitch width has a great impact on electrical masking and latch window masking effects, but they failed to achieve enough insights. In this paper, an analytical glitch generation model is proposed. This model shows that after an inflexion point the collected charge has an exponential relationship with glitch duration and the model only introduces an estimation error of on average 2.5%.

NATURE OF CYCLICAL CHANGES IN THE TIMING RESIDUALS FROM THE PULSAR B1642 – 03

We report an analysis of timing data for the pulsar B1642?03 (J1645 ? 0317) gathered over the 40-year time span between 1969 and 2008. During this interval, the pulsar experienced eight glitch-like events with a fractional increase in the rotation frequency ??/? ~ (0.9-2.6) ? 10?9. We have revealed two important relations in the properties of these peculiar glitches. The first result shows that there is a strong linear correlation between the amplitude of the glitch and the time interval to the next glitch with a slope of about 0.0026 ? 10?9 Hz day?1. This relation allows us to predict epochs of new glitches. The second result shows that the amplitude of the glitches is modulated by a periodic large-scale sawtooth-like function. As a result of this modulation, the glitch amplitude varies discretely from glitch to glitch with a step of 1.5 ? 10?9 Hz in the range (2.4-6.9) ? 10?9 Hz. The post-glitch time interval also varies discretely with a step of ~ 600 days in the range 900-2700 days. An analysis of the data showed that three modulation schemes with modulation periods of 43 years, 53 years, and 60 years are possible. The best model is the 60-year modulation scheme including 12 glitches. We make a conclusion that the nature of the observed cyclical changes in the timing residuals from PSR B1642 ? 03 is a continuous generation of peculiar glitches whose amplitudes are modulated by a periodic large-scale sawtooth-like function. As the modulation function is periodical, the picture of cyclical timing residuals will be exactly repeated in each modulation period or every 60 years.

A CMOS UWB Pulse Generator for 6&amp;#x2013;10 GHz Applications

A CMOS ultra wideband (UWB) pulse generator with low energy dissipation and high peak amplitude is presented for 6-10 GHz applications. The pulse generator complies with the FCC spectral mask for indoor UWB systems. It consists of a glitch generator, a pulsed oscillator, and a pulse shaping filter. The pulsed oscillator is switched on by the glitch signal only for a short duration, so as to make a UWB pulse. For sub-nanosecond pulse generation, a pulsed oscillator with fast transient response is proposed. A pulse shaping filter makes the oscillator output fall into the FCC spectral mask. The pulse generator is fabricated using a 0.18 mum CMOS process. The core chip has a size of 0.11 mm2. It shows pulse duration of about 500 ps with -10 dB bandwidth of 4.5 GHz from 5.9 to 10.4 GHz. The energy consumption is 27.6 pJ per pulse with a peak-to-peak amplitude of 673 mV on a 50 Omega output load. The generated pulses are very coherent with 1.8 ps RMS jitter.

Hydrostatic equilibrium of causally consistent and dynamically stable neutron star models

We show that the mass-radius $(M-R)$ relation corresponding to the stiffest equation of state (EOS) does not provide the necessary and sufficient condition of dynamical stability for the equilibrium configurations, since such configurations can not satisfy the `compatibility criterion'. In this connection, we construct sequences composed of core-envelope models such that, like the stiffest EOS, each member of these sequences satisfy the extreme case of causality condition, $v = c = 1$, at the centre. We, thereafter, show that the $M-R$ relation corresponding to the said core-envelope model sequences can provide the necessary and sufficient condition of dynamical stability only when the `compatibility criterion' for these sequences is `appropriately' satisfied. However, the fulfillment of `compatibility criterion' can remain satisfied even when the $M-R$ relation does not provide the necessary and sufficient condition of dynamical stability for the equilibrium configurations. In continuation to the results of previous study, these results explicitly show that the `compatibility criterion' {\em independently} provides, in general, the {\em necessary} and {\em sufficient} condition of hydrostatic equilibrium for any regular sequence. Beside its fundamental feature, this study can also explain simultaneously, both (the higher as well as lower) values of the glitch healing parameter observed for the Crab and the Vela-like pulsars respectively, on the basis of starquake model of glitch generation.

Transmission Gates Combined With Level-Restoring CMOS Gates Reduce Glitches in Low-Power Low-Frequency Multipliers

Various 16-bit multiplier architectures are compared in terms of dissipated energy, propagation delay, energy-delay product (EDP), and area occupation, in view of low-power low-voltage signal processing for low-frequency applications. A novel practical approach has been set up to investigate and graphically represent the mechanisms of glitch generation and propagation. It is found that spurious activity is a major cause of energy dissipation in multipliers. Measurements point out that, because of its shorter full-adder chains, the Wallace multiplier dissipates less energy than other traditional array multipliers (8.2 mu W/MHz versus 9.6 mu W/MHz for 0.18mum CMOS technology at 0.75 V). The benefits of transistor sizing are also evaluated (Wallace including minimum-size transistors dissipates 6.2 muW/MHz). By combining transmission gates with static CMOS in a Wallace architecture, a new approach is proposed to improve the energy-efficiency further (4.7 muW/MHz), beyond recently published low-power architectures. The innovation consists in suppressing glitches via resistance-capacitance low-pass filtering, while preserving unaltered driving capabilities. The reduced number of V dd-to-ground paths also contributes to a significant decrease of static consumption.

A starquake model for the Vela pulsar

The measured values of the glitch healing parameter, Q, of the Vela pulsar are found to be inconsistent with the starquake mechanism for glitch generation in various neutron star (NS) models, based upon the parametrized equations of state (EOSs) of dense nuclear matter. Such models correspond to an unrealistic mass range ≤0.5 M ⊙ for the pulsar, if the observational constraints of the fractional moment of inertia of the core component (I core /I total ≤ 0.2) which is called the glitch healing parameter, Q, according to the starquake model, are imposed on these models. However, we show that these observational constraints yield a realistic mass range for NS models, corresponding to a core given by the stiffest equation of state, dP/dE = 1 (in geometrized units), and the envelope is characterized by the well-known EOS of an adiabatic polytrope (d In P/d In p = Γ 1 ), if the continuity of the adiabatic speed of sound (υ = dP/dE), together with the pressure (P), the energy density (E) and the two metric parameters (v and λ), is assured at the core-envelope boundary of the models and this boundary is worked out on the basis of the 'compatibility criterion' for hydrostatic equilibrium. The models yield a stable sequence of NS masses in the range 1.758 ≤ M ≤ 2.2 M ⊙ , corresponding to the glitch healing parameter range 0 < Q < 0.197, for a choice of the 'transition density' E b = 1.342 × 10 15 g cm -3 at the core-envelope boundary. The maximum stable value of 2.2 M ⊙ in this sequence, in fact, corresponds to the lowest possible upper bound on NS masses calculated in the literature, on the basis of modem EOSs for NS matter. The models yield the surface redshift z R ≃ 0.6913 and mass M ≃ 2.153 M ⊙ for the 'central' weighted mean value, Q = 0.12 ± 0.07, of the glitch healing parameter of the Vela pulsar. This value of mass can increase slightly up to M ≃ 2.196 M ⊙ , whereas the surface redshift can increase up to the value z R ≃ 0.7568 [which represents an ultracompact object (zR ≥ 0.73)], if the observational constraint of the upper weighted mean value of Q ≃ 0.19 is imposed on these models. However, for the lower weighted mean value of Q ≃ 0.05, the mass and surface redshift can decrease to the values of z R ≃ 0.6066 and M ≃ 2.052 M ⊙ respectively. These results set the lower bound on the energy of gravitationally redshifted radiation in the rather narrow range of 0.291-0.302 MeV. The observation of the lower bound on the energy of a γ-ray pulse at about 0.30 MeV from the Vela pulsar in 1984 is in excellent agreement with this result, provided that this energy can be interpreted as the energy of gravitationally redshifted electron-positron annihilation radiation from the surface of the star.

A Complete Model for Glitch Analysis in Logic Circuits

One of the major factors, which contribute to the power consumption in CMOS combinational logic circuits, is the switching activities in the circuits. Many of such switching activities are due to spurious pulses, called glitches. Recently, a new model of glitch analysis, called G-vector has been proposed. The power of the model is that, unlike the existing ones, which model only the propagation of glitches to count the number of glitches in the circuits, it allows to model the generation, propagation and elimination of glitches to be able to not only count the number of glitches but also locate the glitches. In this paper, we complete the concept of G-vector by providing a set of efficient solutions to the three important practical issues: (1) extending to signals over multiple clock cycles, which exactly accounts for a sequence of input signals over multiple clock cycles. (2) extending to a nonzero delay model, which accounts for both nonzero and nonuniform delay of each gate in the circuit and (3) extending to a logic decomposition utilizing the model, which reveals a possibility of utilizing the model in synthesizing logic circuit with less glitches. Integrating the solutions all together enables G-vector to be practically very efficient. A set of experimental results is provided to show the effectiveness of the proposed solutions.

A COMPLETE MODEL FOR GLITCH ANALYSIS IN LOGIC CIRCUITS

One of the major factors, which contribute to the power consumption in CMOS combinational logic circuits, is the switching activities in the circuits. Many of such switching activities are due to spurious pulses, called glitches. Recently, a new model of glitch analysis, called G-vector has been proposed. The power of the model is that, unlike the existing ones, which model only the propagation of glitches to count the number of glitches in the circuits, it allows to model the generation, propagation and elimination of glitches to be able to not only count the number of glitches but also locate the glitches. In this paper, we complete the concept of G-vector by providing a set of efficient solutions to the three important practical issues: (1) extending to signals over multiple clock cycles, which exactly accounts for a sequence of input signals over multiple clock cycles. (2) extending to a nonzero delay model, which accounts for both nonzero and nonuniform delay of each gate in the circuit and (3) extending to a logic decomposition utilizing the model, which reveals a possibility of utilizing the model in synthesizing logic circuit with less glitches. Integrating the solutions all together enables G-vector to be practically very efficient. A set of experimental results is provided to show the effectiveness of the proposed solutions.

G-vector: A New Model for Glitch Analysis in Logic Circuits

One of the major factors which contribute to the power consumption in CMOS combinational logic circuits is the switching activities in the circuits. Many of such switching activities are due to spurious pulses, called glitches. In this paper, we propose a new model for describing signals that contain glitches, called G-vector. Unlike the previous works in which their primary concern is modeling the propagation of glitches to count the number of glitches in the circuits, our G-vector provides a general, but effective model for generation, propagation and elimination of glitches, enabling us to not only count the number of glitches but also locate the glitches so that such information can be utilized by system tools for the reduction of the number of glitches in the circuits. We provide a set of experimental results to demonstrate the effectiveness of our model.

Switching activity estimation under real-gate delay using timed Boolean functions

A probabilistic method to estimate the switching activity of a combinational circuit under a real-gate delay model considering temporal, structural and input pattern dependencies is introduced. It is proved that the switching activity evaluation problem is reduced to the zero-delay problem at specific time instances. A mathematical model based on Markov stochastic processes, which describes the temporal and spatial correlation in terms of the associated zero-delay parameters, is presented. To handle the influence of time on glitch generation, the theory of the timed Boolean function (TBF) is adopted. Additionally, an algorithm to evaluate the switching activity at specific time instances using TBF-ordered binary decision diagrams (TBF-OBDDs) is given. Comparative study of benchmark circuits demonstrates the accuracy and efficiency of the proposed method.