Gate Delay Research Articles

Comparative analysis of optical gating time characterization methods for ultrafast gated image intensifiers with sub-nanosecond temporal resolution

Ultrafast gated image intensifiers are crucial for capturing high-resolution images with sub-nanosecond temporal resolution. This study compares two methods for characterizing optical gating time in these intensifiers: Method I, involving a “laser pulse walkthrough,” and Method II, utilizing a fiber optic delay array. Both methods were applied to the same intensifier, with results analyzed for consistency and discrepancies. The findings indicate that both methods yield consistent optical gating times within their standard deviations range, though Method II exhibited greater dispersion at the photocathode edges due to spatial non-uniformity. The study further reveals that while the optical gating time distribution across the photocathode is uniformly consistent, a constant delay exists between different regions. To enhance measurement precision it is recommended to subdivide the photocathode for individual calibration of gating time and delay. These insights are pivotal for improving the precision and reliability of optical gating time measurements in applications requiring sub-nanosecond or even picosecond temporal resolution.

A Gate-Level Power Estimation Approach with a Comprehensive Definition of Thresholds for Classification and Filtering of Inertial Glitch Pulses

Estimation of power consumption in digital circuits is performed at gate-level simulation. Its accuracy depends on the models of gate delays that capture the effects of spurious signal transitions, called “glitches”. Electronic Design Automation (EDA) software considers inertial gate delays and represses a glitch in the cell’s output if its width is below a threshold. Selecting threshold values for the inertial glitch classification and filtering is crucial for precise power estimations. In this direction, we explore the effectiveness of automatically adjusting such thresholds on a cell-specific basis according to the local cell’s information. We used a commercial industry-standard gate-level power estimation tool and a 32 nm CMOS standard cell library. Via power measurements in circuit simulations, we created customized lookup tables for each library cell employed in the benchmark circuits. We compared the proposed approach’s performance with other methods for glitch threshold definition. Our method demonstrated good power estimation accuracy while presenting the lowest mean absolute error among all the cells of the circuits under test and the smallest standard deviation. The latter suggests that the proposed method achieves better cell-specific accuracy, which is expected to allow for more precise circuit-level power estimations in complex circuits with a large number of combinational cells.

Optimizing integrated circuits: Design and analysis of an efficient 4-bit absolute-value detector

Amidst rapid advancements in the realm of computer science, integrated circuits emerge as pivotal to technological progression, influencing a diverse range of sectors significantly. This study delves into a 4-bit absolute-value detector, a crucial tool in signal detection, which evaluates the magnitude of a given inputs absolute value against a predetermined threshold and conveys the outcome. The paper presents an innovative, optimized design for a 4-bit absolute-value detector, employing CMOS technology. A novel, efficient 3-bit adder is developed and incorporated in the circuit to minimize gate delay and energy usage. By fine-tuning the applied voltage (Vdd) and implementing gate sizing, the delay is maintained at approximately 1.5 times the minimum possible delay, while ensuring low power consumption. The defined parameters for this detector are 145.05 FO4 (0.82V) and 7.23C Eu (0.82V). The design methodologies and strategic insights shared in this paper form a foundational basis for future enhancements in signal processing technologies, potentially driving these fields towards a path of accelerated, robust, and sustainable growth.

Elemental quantitation and evaluation of hydrocarbon in shale using fiber-optic laser induced breakdown spectroscopy

To meet the demands of in situ analysis, a fiber-optic laser-induced breakdown spectroscopy (FO-LIBS) system was established to predict the elemental concentrations and pyrolytic parameters. The key parameters, including pulse energy, gate delay, type of surrounding gas, and flow rate of gas, were optimized to improve the signal-to-noise ratio of the spectral lines, and the evolution characteristics of the plasma morphology in different gas atmospheres were investigated. Under the optimized experimental conditions, C, H, Si, Ca, Fe, and Mg were calibrated using pellet samples based on partial least squares regression, and the average relative prediction error of the natural samples was lower than 10%. In addition, the support vector regression method was utilized to predict pyrolytic parameters such as TOC, Pg, and Tmax with the R2 of all calibration curves being higher than 0.97. The abundance and generation potential of hydrocarbons were evaluated using the predicted TOC and Pg, and Tmax could contribute to the thermal maturity of the kerogen.

Laser-induced breakdown spectroscopy (LIBS) of animal fat (lard): Efficient sample preparation for onsite analysis and influence of sample temperature on the signal intensity and plasma parameters

We report an efficient sample preparation method (freezing) for onsite fat and meat analysis via a specially designed thermoelectric cooling and temperature-controlling system. This investigation also focused on the effect of phase change on the sensitivity and reproducibility of LIBS emission signals and plasma parameters. The plasma emissions of animal fats (lard) were recorded when the sample was frozen (−2 °C), fluid (15 °C), and in a liquid state (37 °C) with a thermoelectric cooling system. At each temperature, the plasma emissions were acquired at laser pulse energy from 50 to 300 mJ and detector gate delay (DGD) from 0.5 to 5 μs. With increasing sample temperature, the DGD, where the optical emission intensity reached a maximum, decreased. At a laser pulse energy of 200 mJ and a sample temperature of −2 °C, the emission signals increased fourfold, the signal-to-noise ratio (SNR) improved tenfold, and the self-absorption in the emission lines decreased significantly. The repeatability of the emission signals and plasma parameters of frozen and liquid fat samples was determined using the relative standard deviation (RSD) of Se I (473.08 nm) and K I (766.48 nm) emission lines. The RSDs of the emission signals improved from 40 to 18 % and 37 to 16 %, whereas the shot-to-shot RSDs of the electron temperature and electron number density get improved from 11 to 6 % and 12 to 6.8 %, respectively.

Self-absorption of emission lines in picosecond-laser-produced gold plasmas

Ultrashort laser ablation offers several advantages in various applications compared to traditional nanosecond laser ablation techniques. Despite providing a lower damage threshold, cold ablation with high precision, the impact of self-absorption effects in ultrashort laser-produced plasmas (LPPs) significantly affects the assessment of plasma parameters and analytical outcomes in Laser-Induced Breakdown Spectroscopy (LIBS) analysis. This study investigated the impact of laser energy, analyte concentration, and acquisition gate delay on the self-absorption of emission lines from picosecond LPPs (ps-LPPs) of gold targets at atmospheric pressure. We used four gold targets (24 carat gold, 22 carat gold, 18 carat gold, and Hepatizon) with varying concentrations of gold and copper. To analyze the self-absorption effects in ps-LPP, we examined four neutral emission lines of ps-LIBS spectra (Au I: 267.59 and 627.81 nm; Cu I: 327.98 and 510.55 nm). We observed that with an increase in laser pulse energy, there is a corresponding rise in the self-absorption of emission lines under ambient pressure. This increase in analyte species concentration leads to an elevation in the self-absorption of emission lines. Additionally, as the temporal delay of acquisition extends, self-absorption intensifies.

Aligned carbon nanotube-based electronics on glass wafer.

Carbon nanotubes (CNTs), due to excellent electronic properties, are emerging as a promising semiconductor for diverse electronic applications with superiority over silicon. However, until now, the supposed superiority of CNTs by "head-to-head" comparison within a well-defined voltage range remains unrealized. Here, we report aligned CNT (ACNT)-based electronics on a glass wafer and successfully develop a 250-nm gate length ACNT-based field-effect transistor (FET) with an almost identical transfer curve to a "90-nm" node silicon device, indicating a three- to four-generation superiority. Moreover, a record gate delay of 9.86 ps is achieved by our ring oscillator, which exceeds silicon even at a lower supply voltage. Furthermore, the fabrication of basic logic gates indicates the potential for further digital integrated circuits. All of these results highlight ACNT-based FETs on the glass wafer as an effective solution/platform for further development of CNT-based electronics.

Modeling of inner-outer gates and temperature dependent gate-induced drain leakage current of junctionless double-gate-all-around FET

In this paper, the temperature-dependent gate-induced drain leakage (GIDL) current model is proposed with the help of a lateral electric field (EL) across the inner and outer gate interfaces of the junctionless double-gate-all-around (JL-DGAA) field-effect transistor (FET). The EL at the interface is obtained from the surface potential equation after solving the 3D Poisson equation with appropriate boundary conditions. The derived model is validated using the well-calibrated TCAD simulator platform with experimental data. A higher GIDL current at the outer gate-channel interface is observed compared to the inner gate-channel interface in the OFF-state conditions due to the high EL between the channel and drain, which is reported for the first time here. The effect of temperature (from 200 K to 500 K) on the GIDL current is also observed, which increases linearly with increasing temperature. Further, the impact of induced mechanical stress (MS) is investigated on the GIDL current, where the GIDL current increases exponentially with increasing induced MS due to effective mass and band gap reduction. Finally, the dynamic performance is investigated in terms of the gate delay time as a function of channel length and temperature. The gate delay diminishes with decreasing channel length and increasing temperature, which shows the switching speed and ability of the device.

Study of spectral lines behaviour with a double pulse 1064–1064 nm laser-induced breakdown spectroscopy system at the direct analysis of algae on the filter

The nickel and zinc contamination of algae on a cellulose filter was studied with double pulse 1064–1064 nm laser-induced breakdown spectroscopy (LIBS). Samples of the green alga Desmodesmus subspicatus were contaminated with zinc and nickel. The surface concentrations on the filter calculated from the reference Inductively Coupled Plasma Mass Spectrometry analysis were 25 and 64 ng cm−2 for nickel and zinc respectively. The algae are resting on the filter after drying and a double adhesive tape was used to fix the sample on the microscopic glass. During optimization method a compromise of 23–30 mJ pulse energies were set for maintaining a detectable or highest signal intensity of the analyte and not destroying the filter. Best conditions for maximum analyte signal and minimum deviation between the spectral behaviour of the analyte and the compared line of Na I, K I, Mg I, Mg II, Mn I, Mn II, Ca I, Ca II, and C I was 700 ns gate delay and 0 s interpulse delay. The deviation was rather more influenced with the signal-to-noise ratio of the analyte line than the closeness of the upper-level energies of the compared lines. The filter without algae showed systematically lower electron number density and total emissivity by units of percents than the filter with algae.

Compensating isotope effect on molecular emission of hydroxyl and imidogen isotopologues in laser-induced plasma

BackgroundThe molecular isotopologues in laser-induced plasma exhibit riddling emission behaviors in terms of wavelength, intensity, and temporal evolution of spectra due to the isotope effect. Although this phenomenon introduces uncertainty to isotope analyses based on molecular spectra, its underlying mechanism remains undisclosed. ResultsIn this study, laser-induced breakdown spectroscopy (LIBS) is employed to identify the emission behavior of hydrogen, oxygen, and nitrogen isotopologues in a plasma plume. The goal is to discern the details of the isotope effect and mitigate resulting uncertainty. The molecular emissions of hydroxyl (OH) and imidogen (NH) were measured from plasma ablated on isotopically enriched water samples. Time-resolved detection clearly reveals distinct isotopic disparities in intensity variation and optimum gate delay, which were attributed to plasma thermo-hydrodynamics. Lighter isotopologues exhibit earlier and faster associations than their heavier counterparts due to their fast reaction rates and expansion velocities. The extent of the isotope effect hinged on plasma characteristics governed by measurement conditions. Consequently, comparing spectral intensity between molecular isotopologues cannot directly indicate the nominal isotope abundance of the sample. To address it, a compensation strategy has been devised, quantifying isotope effects through parameters like the slope and optimum delay of time-resolved detection. The approach successfully predicts nominal isotope abundance using compensated intensity ratios, with an absolute bias of less than 3 %. SignificanceThis study not only offered fundamental insights into the isotope effect in laser-induced plasma but also proposed an alternative method for isotope quantification that circumvents complicated calibration processes.

Investigating the effects of laser wavelengths and other ablation parameters on the detection of biogenic elements and contaminants in hydroxyapatite

A comparison of laser ablation measurement parameters (laser wavelength, energy, gate delay, defocus, and spot size) to determine optimal settings for the detection of heavy metals and biogenic elements in a hard tissue matrix (hydroxyapatite).

Jitter due to Random Telegraph Noise: a Study on the Time Dependent Variability of a Ring Oscillator

Random Telegraph Noise is a relevant source of variability in integrated circuits and a growing issue due to device scaling. Jitter is one of its consequences; therefore, it is an important parameter of performance measurements for electronic components and systems. In this paper, the relationship between Random Telegraph Noise and different concepts of jitter is studied. Firstly, a gate delay variability study of a CMOS inverter is discussed. Then, an absolute, a periodic, and a cycle-to-cycle jitter are evaluated in a five-stage ring oscillator. All the data were generated with a spice simulator modified to properly account for Random Telegraph Noise, using the Monte Carlo technique.

Formulation of the airport collaborative gate allocation problem and the Bee Colony Optimization solution approach

This article formulates the Collaborative Gate Allocation (CGA) problem as a novel concept to reduce aircraft gate-waiting time and to increase aircraft gate utilization. The proposed CGA concept assumes voluntary collaboration and negotiation among airlines and airport operators, enabling them to share real-time information on gate-utilization and gate-sharing. The proposed policy is especially applicable to U.S. airports, as an alternative to exclusive or preferential gate-sharing practices, at terminal buildings that accommodate a large number of smaller airlines during periods of high congestion and delays caused by high traffic demands, bad weather conditions, or any ad hoc situations. The CGA problem belongs to the class of complex combinatorial optimization problems, whose optimal solution is difficult to discover. This article develops a Swarm Intelligence-based model for the CGA problem. Our approach to solving the CGA problem is based on the Bee Colony Optimization (BCO) metaheuristic. The BCO algorithm belongs to the class of population-based algorithms. This technique uses a similarity between the way in which bees in nature look for nectar, and the way in which optimization algorithms search for an optimum solution to a combinatorial optimization problem. Numerical experiments are performed using Denver International Airport as a real-world case study. We show that the proposed CGA problem can be efficiently solved by our BCO algorithm, and that applications of the CGA concept can significantly reduce gate delays.

Effects of metal work function and gate-oxide dielectric on super high frequency performance of a non-align junction DG-MOSFET based inverter in the sub-100 nm regime: a TCAD simulation analysis

ABSTRACT This paper presents simulation analysis of an inverter made from non-aligned double gate field effect transistors (NADGFETs) in Sub-100 nm regime. The inverter consists of n-channel NADGFET and p-channel NADGFET device with a channel length of 40 nm and 50% non-alignment between gate and source/drain. The response of the inverter was tested by a combination of gate dielectric constant (k) and metal work function (ϕ). Three gate dielectrics namely, SiO2 (k = 3.9), Si3N4 (k = 7.2), HfO2 (k = 24), and three metal work function namely tungsten (ϕ = 4.5 eV), molybdenum (ϕ = 4.75 eV), gold (ϕ = 5 eV), were considered in the NADGFET inverter. This paper defines a kϕ index as characterising parameter to explore the best response from inverter configuration with minimum propagation delay, and minimum power consumption at super-high frequency. The paper proposes to analyse the NADGNFET device, in term of ION current, ION/IOFF ratio, cut-off frequency, and gate delay. And observes that low k material with moderate metal work function gives best response. The work then simulates the inverter and group the results into voltage transfer curve (VTC), transient response, and power dissipation category. The result shows that when inverter was subjected to high frequency, all the kϕ combination responds good, however when the inverter was subjected to super-high frequency, the low value of kϕ combination performs well. Thus, the result concludes that SiO2-M2 combination will be best selection to get minimum propagation delay and dynamic power dissipation by the inverter. The test strategy presented in this paper on the basis of kϕ index can serve as benchmark to test inverter device at super-high frequency.

Fabrication and performance of highly stacked GeSi nanowire field effect transistors

AbstractHorizontal gate-all-around field effect transistors (GAAFETs) are used to replace FinFETs due to their good electrostatics and short channel control. Highly stacked nanowire channels are widely believed to enhance drive current of these devices and improve overall transistor density due to their small footprint. Here we demonstrate the fabrication and characterization of nanowire FETs with stacked 16 Ge0.95Si0.05 nanowires and stacked 12 Ge0.95Si0.05 nanowires without parasitic channels. The device has the high on current (ION) of 190 μA per stack (9400 μA/μm per channel footprint) at overdrive voltage (VOV) = drain-source voltage (VDS) = 0.5 V and the high maximum transconductance (Gm,max) of 490μS (24000μS/μm) at VDS = 0.5 V among reported Si/Ge/GeSi 3D nFETs. Note that the transistor performance can be evaluated by the delay, which is depicted as CV/I. If the transistor ION is improved, the delay of standard cell can be reduced, leading to faster operation of the circuit. The subthreshold slope reduction and ION/IOFF improvement are achieved by the parasitic channel removal. In technology computer aided design (TCAD) simulation, the wrap around contacts are useful to reduce the current difference between the channels. With the proper design of transistor height, the gate delay can be also improved.

Delay Cell for Highly-Linear Current-Controlled Oscillator-Based Analog-to-Digital Conversion

A delay cell is presented to implement highly-linear current-controlled ring oscillators as used in analog-to-digital converters. It consists of a NOT gate whose propagation delay is controlled by an input current, and two extra NOT gates with constant supply voltage configuration. Under well-controllable conditions the propagation delay of the first NOT gate can be set much longer than the delay of the other two NOT gates, leading to a linear relation between the input current and the oscillation frequency, hence significantly reducing the total harmonic distortion for single-ended architectures. A prototype of a 5-stage current-controlled ring oscillator has been designed and manufactured in a 65-nm CMOS technology, and validated experimentally. Several samples of the prototype design have been measured, showing a high robustness against PVT variations without requiring any type of calibration. The ring oscillator occupies only 0.00094 mm, consumes 22 μW, and has a worst-case of total harmonic distortion equal to -59 dBc (0.6% of relative nonlinearity error).

Influence of sample temperature and ambient argon pressure on LIBS spectra of extracted animal fat

This work explores the influence of sample temperature, ambient gas pressure, laser energy, and detector gate delay (DGD) on the LIBS emissions of extracted animal fat. The emissions from laser-induced plasma of extracted animal fat were acquired with varying sample temperatures, ambient argon pressure, laser energy, and detector gate delay. A thermoelectric system fitted with a temperature-controlling sensor was used to control the sample temperature. For maximum optical emission intensity, the detector gate delay (DGD) shifted toward a lower value with the increase in sample temperature for all ambient argon pressures. The nine-fold signal enhancement, ten times improvement in signal-to-noise ratio (SNR), and significantly reduced self-absorption were observed in all detected emission lines recorded at 200 mJ laser energy –2 ºC sample temperature, 375 Torr ambient argon pressure, and 2 µs DGD. The repeatability of emission signals was evaluated by calculating the relative standard deviation (RSD) of the emission line (Zn I (636.23 nm)) at different sample temperatures, which improved from 35 % to 6 % when the sample changed from liquid to solid (frozen). During the semi-liquid form of fat, the decreasing ambient gas pressure did not significantly affect signal repeatability. In addition to diagnosing the fat plasma, the plasma temperature and electron number density have been evaluated as a function of sample temperature and ambient argon pressure.

Characterization of a Low-Temperature Plasma (LTP) Ambient Ionization Source Using Temporally Resolved Monochromatic Imaging Spectrometry.

The low-temperature plasma (LTP) probe is a common plasma-based source used for ambient desorption-ionization mass spectrometry (MS). While the LTP probe has been characterized in detail with MS, relatively few studies have used optical spectroscopy. In this paper, two-dimensional (2D) imaging at selected wavelengths is used to visualize important species in the LTP plasma jet. First, 2D steady-state images of the LTP plume for N2+ (391.2 nm), He I (706.5 nm), and N2 (337.1 nm) emissions were recorded under selected plasma conditions. Second, time-resolved 2D emission maps of radiative species in the LTP plasma jet were recorded through the use of a 200 ns detection gate and varying gate delays with respect to the LTP trigger pulse. Emission from He I, N2+, and N2 in the plasma jet region was found to show a transient behavior (often referred to as plasma bullets) lasting only a few microseconds. The N2+ and He I maps were highly correlated in spatial and temporal structure. Further, emission from N2 showed two maxima in time, one before and one after the maximum emission for N2+ and He I, due to an initial electronic excitation wave and ion-electron recombination, respectively. Third, the interaction of the LTP probe with a sample substrate and an electrically grounded metallic needle was studied. Emission from a fluorophore on the sample substrate showed an initial photon-induced excitation from plasma-generated photons followed by electronic excitation by other plasma species. The presence of a grounded needle near the plasma jet significantly extended the plasma jet lifetime and also generated a long-lived corona discharge on the needle. The effect of LTP operating parameters on emission spectra was correlated with mass-spectral results including reagent-ion signals. Lastly, five movies provide a side-by-side comparison of the temporal behavior of emitting species and insights into the interactions of the emission clouds with a sample surface as well as an external needle. Temporally and spatially resolved imaging provided insights into important processes in the LTP plasma jet, which will help improve analyte ion sampling in LTP-MS.

Flight Time and Flight Traffic Before, During, and After the Pandemic: What Has Changed?

This paper develops a model for quantifying the relationship between flight volume and its operational performance at the macro level and investigating whether there are any changes before, during, and after the pandemic. Inspired by the market basket concept from economics, we first calculate macro-level effective flight time (EFT) for the U.S. domestic flight market by constructing a flight basket. Semi-log-linear models are developed to formulate the relationship between the total number of flights and macro-level EFT and its components. The estimation results indicate that the total number of flights has a positive and significant impact on EFT and its components, with 29.244 min longer for the weighted EFT for the analysis period compared with a zero-traffic scenario. Further investigations into the post-pandemic period verify the performance of the model and indicate that deteriorating operational performance in this period, especially with regard to gate delay and taxi-in time, is not only a result of the recovery of the flight market.

An 8-bit TDC implemented with two nested Johnson counters

This work presents a Time-to-Digital Converter implemented using two nested Johnson counters and suitable for time-lapse measurement applications. The proposed structure is composed of two 4-bit nested counters, two digital-logic control networks, two registers and a single decoder. Semi-dynamic logic was used for the decoder to reduce its power consumption. The system has a standard digital output and is powered by a 1.8 V supply with a total power consumption of 32.4 mW. A prototype was fabricated using a TSMC 180 nm CMOS technology. The proposed structure uses a 508 µm x 225 µm area. In addition, this TDC has a standard deviation of 0.78 LSB with a fixed input time interval operating at a frequency of 1 MHz. The proposed structure shows good performance results and repeatability for continuous conversion conditions, these results are attributed to the simplicity of the system and the use of counters with minimum gate delay as the main elements for the TDC.