Propagation Delay Characteristics Research Articles

On the propagation delay of CMOS inverters

This research study delves into the propagation delay analysis in Complementary Metal-Oxide-Semiconductor (CMOS) inverters, aiming to uncover the factors contributing to it and exploring strategies to mitigate its impact. CMOS inverters, as pivotal constituents within digital integrated circuits, play a foundational role, making a thorough understanding of their propagation delay characteristics indispensable for the design of high-performance circuit. The research encompasses a comprehensive examination of propagation delay in CMOS inverters, addressing three key factors affecting it: load capacitance, transconductance parameters, and power supply voltage. Additionally, the study explores techniques for reducing propagation delay, including leveraging alternative materials and adopting specific layout designs. This study can provide insights into the sources of propagation delay in CMOS inverters and provide a comprehensive grasp of methods to alleviate it. By efficiently managing propagation delay, it becomes possible to enhance the overall performance and efficiency of CMOS circuits, thereby facilitating the development of advanced, high-speed digital systems.

Characteristic analysis and simulation of a Cu-graphene hybrid nanointerconnect under different Drude models

It is well known that the ultra thin barrier layer around the Cu nanointerconnect has a great impact on its performance. Currently, graphene is the thinnest two-dimensional material. Cu-graphene hybrid nanointerconnects can significantly advance the potential of integrated cirCuit technology. In this article, we put a monolayer graphene on the top, left and right sides of a Cu nanointerconnect. graraphene adopts three Drude models, namely, the Drude model obtained by simplified Kubo formula, the Drude-Lorentz model, and the Drude model derived from Boltzmann equation. We use cst to simulate the voltage-current variation and propagation delay characteristics of a Cu-graphene hybrid nanointerconnect are observed under three Drude models and compared with a Cu nanointerconnect. Finally, the Drude model of graphene which is derived from the Boltzmann transport equation can minimize the voltage of the Cu nanointerconnect and reduce the propagation delay of the two ports of the Cu nanointerconnect.

Device and Circuit Level Assessment of Negative Capacitance TFETs for Low-Power High-Performance Digital Circuits

In this paper, we propose and analyse the performance of negative capacitance tunnel field-effect-transistors (NC-TFETs) at device and circuit level. We design and simulate four NC-TFETs, two are Silicon based “Si NC N-TFET,” “Si NC P-TFET” and two are Heterojunction Silicon-Germanium source based “SiGe NC N-TFET,” “SiGe NC P-TFET.” The effect of NC is incorporated with 5 nm thick layer of ferroelectric Hafnium Zirconium Oxide HfZrO2 (FE-HZO) in gate stack of TFETs by using of Landau-Khalatnikov (L-K) equations in MATLAB. The results show that at reduced NC gate voltage, the ON current (ION), On to OFF current (ION/IOFF) in NC devices is enhanced by while reduction in the threshold voltage (VTH) and Average subthreshold slope (SSAV) is observed. The SiGe NC-TFETs showed the best response with maximum ION range, ION/IOFF ratio of lowest SS as compare to Si NC-TFETs. The circuit transient analysis is done using the Verilog-A model based on look-up table (LUT) approach. The propagation delay of NC NAND circuits is reduced 90%, the SiGe NC-TFETs based circuits showing the smallest propagation delay and fast transient characteristics. This paper also demonstrates that the impact of FE-HZO thickness (TFE) on the device-circuit characteristics.

Nonambiguous Image Formation for Low-Earth-Orbit SAR With Geosynchronous Illumination Based on Multireceiving and CAMP

Low-earth-orbit (LEO) synthetic aperture radar (SAR) can achieve advanced remote sensing applications benefiting from the large beam coverage and long duration time of interested area provided by a geosynchronous (GEO) SAR illuminator. In addition, the receiving LEO SAR system is also cost-effective because the transmitting module can be omitted. In this article, an imaging method for GEO-LEO bistatic SAR (BiSAR) is proposed. First, the propagation delay characteristics of GEO-LEO BiSAR are studied. It is found that the traditional “stop-and-go” propagation delay assumption is not appropriate due to the long transmitting path and high speed of the LEO SAR receiver. Then, an improved propagation delay model and the corresponding range model for GEO-LEO BiSAR are established to lay the foundation of accurate imaging. After analyzing the sampling characteristics of GEO-LEO BiSAR, it is found that only 12.5% sampling data can be acquired in the azimuth direction. To handle the serious sub-Nyquist sampling problem and achieve good focusing results, an imaging method combined with multireceiving technique and compressed sensing is proposed. The multireceiving observation model is first obtained based on the inverse process of a nonlinear chirp-scaling imaging method, which can handle 2-D space-variant echo. Following that, the imaging problem of GEO-LEO BiSAR is converted to an $L_{1}$ regularization problem. Finally, an effective recovery method named complex approximate message passing (CAMP) is applied to obtain the final nonambiguous image. Simulation results show that the proposed method can suppress eight times Doppler ambiguity and obtain the well-focused image with three receiving channels. With the proposed method, the number of required receiving channels can be greatly reduced.

Propagation Delay Characteristics Analysis in LEO Satellite Multi-Beam Antenna Coverage

In this paper a calculation model of propagation delays of satellite beams is introduced for LEO multi-beam satellite communications system. Based on actual parameters and beam coverage patterns of the Iridium and Globalstar system, the maximum propagation delay differentials in several typical beams from the center to the edge of the satellites coverage are calculated. Analysis of these results can provide reference for analyzing the feasibility of LEO multi-beam satellite system compatible with uplink synchronization in LTE.

The Measurement and Time Series Analysis of Loran C Ground Wave Propagation Delay

In order to effectively correct the positioning error of Loran C to improve the positioning accuracy, it is necessary to study Loran C ground wave signal propagation delay variation with time, study the stability of propagation delay and timing characteristics. Take statistical analysis and pretreatment to Loran C ground wave signal propagation delay, test its stationarity, extraction its trend term, obtain stationary series, modeling to trend term and stationary series. The results show that Loran C ground wave signal propagation delay has good stability and repeatability, the time delay series can be fitted to combination model formed by G (2,1) cycle model and AR (p) from the regression model.

The Measurement and Time Series Analysis of Loran C Ground Wave Propagation Delay

In order to effectively correct the positioning error of Loran C to improve the positioning accuracy, it is necessary to study Loran C ground wave signal propagation delay variation with time, study the stability of propagation delay and timing characteristics. Take statistical analysis and pretreatment to Loran C ground wave signal propagation delay, test its stationarity, extraction its trend term, obtain stationary series, modeling to trend term and stationary series. The results show that Loran C ground wave signal propagation delay has good stability and repeatability, the time delay series can be fitted to combination model formed by G (2,1) cycle model and AR (p) from the regression model.

TEMPERATURE-ADAPTIVE ENERGY REDUCTION TECHNIQUES FOR NANO-CMOS CIRCUITS DISPLAYING REVERSED TEMPERATURE DEPENDENCE

Temperature dependent propagation delay characteristics of CMOS circuits will experience a complete reversal in the near future. Contrary to the older technology generations, the speed of circuits in a 32nm CMOS technology is enhanced when the temperature is increased at the nominal supply and threshold voltages. The enhancement of circuit speed provides new opportunities to lower the energy consumed by active circuits at elevated temperatures. Temperature-adaptive supply and threshold voltage tuning techniques are proposed in this paper to reduce the high temperature energy consumption without degrading the clock frequency in the active mode. Results indicate that the energy consumption can be lowered by up to 21% by dynamically scaling the supply voltage at elevated temperatures. An alternative technique based on temperature-adaptive reverse body-bias exponentially reduces the leakage currents as well as the parasitic junction capacitances of the MOSFETs. The temperature-adaptive threshold voltage tuning through reverse body-bias yields an active mode energy reduction by up to 29.8% as compared to the standard zero-body-biased circuits at high temperatures.

Reversed Temperature-Dependent Propagation Delay Characteristics in Nanometer CMOS Circuits

The supply voltage to threshold voltage ratio is reduced with each new technology generation. The gate overdrive variation with temperature plays an increasingly important role in determining the speed characteristics of CMOS integrated circuits. The temperature-dependent propagation delay characteristics, as shown in this brief, will experience a complete reversal in the near future. Contrary to the older technology generations, the speed of circuits in a 45-nm CMOS technology is enhanced when the temperature is increased at the nominal supply voltage. Operating an integrated circuit at the prescribed nominal supply voltage is not preferable for reliable operation under temperature fluctuations. A design methodology based on optimizing the supply voltage for temperature-variation-insensitive circuit performance is proposed in this brief. The optimum supply voltage is 45% to 53% lower than the nominal supply voltage in a 180-nm CMOS technology. Alternatively, the optimum supply voltage is 15% to 35% higher than the nominal supply voltage in a 45-nm CMOS technology. The speed and energy tradeoffs in the supply voltage optimization technique are also presented

BLAST: broadband lightweight ATM secure transport for high-performance distributed computing

This paper investigates the use of ATM for cluster-based computing. The need for a native ATM API is discussed as well as the performance of message passing libraries (MPL) that are written to use such an API to exploit the advantages of a high-speed network for cluster-based computing. The MPLs offer a standard interface, such as PVM or MPI, and interoperate with existing TCP/IP- and UDP/IP-based versions in addition to the ATM API environment. The interoperability extensions made to two MPLs, MPI and Prowess, which allow a hybrid environment of both ATM and TCP-based legacy network technology will be described. Shared object space (SOS), an extension to the MPLs, is described that helps support the geographically distributed computing (GDC) environment through latency hiding. It allows a user to develop applications in a shared memory type of environment. The native ATM API which supports cluster-based computing is described in this paper. This API provides a reliable transport interface to the MPL which has been optimized for an ATM environment. The transport protocol is a low-state design that optimizes the performance based on the available bandwidth, buffer constraints, propagation delay characteristics and security requirements of a particular connection. © Elsevier Science B.V.

Indoor propagation calculation taking into account antenna patterns using geometrical optics method

AbstractAn algorithm to compute the effects of the radiation patterns and polarizations of arbitrary transmit and receive antenna is added to the conventional geometrical optics analysis procedure to study indoor propagation delay characteristics. A method is presented in which the angular information needed for the calculations of the foregoing in a rectangular room can be derived easily from the geometrical nature of the room. By moans of the present procedure, the delay wave suppression effect of a narrow‐beam antenna in a multipath propagation environment is shown quantitatively. For instance, in the case where both transmit and receive antennas are omnidirectional, the delay spread can be reduced to almost one‐tenth if a pencil beam with a half‐power beamwidth of 30° is used. By means of these results, a design procedure for antenna half‐power beamdwidth and the polarization was developed for realization of high‐transmission quality in an indoor high‐speed wireless data communication.

Performance analysis of multilayer interconnections for megabit static random access memory chip

Interconnections problems in the megabit static random access memory (SRAM) chip are studied. A multilayer interconnect capacitance model is developed, and effects of interconnection on SRAM device performance parameters, such as propagation delay, speed, power consumption, and noise characteristics, are analyzed. A case study of 1-Mb SRAM chip interconnection is discussed. A multilayer interconnect approach is proposed to overcome on-chip interconnection difficulties. By implementing a double-layer interconnect approach, the wire length and chip size were reduced to 69% and 58%, respectively. Maximum access time of 30.8 ns with 1 W at 100 degrees C and wafer yield as high as 10% was achieved.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Long-term propagation delay characteristics of telecommunication lines

The variations in outgoing path delay and incoming delay of a paired transmission path have been measured simultaneously and independently for over one year. The characteristics will allow the performance of delay compensation schemes for precise time synchronization of digital telecommunication networks to be evaluated. The annual delay variation is caused by temperature changes, and its magnitude is about 3 mu s for the 2400-km line investigated. It is shown that the variation of annual delay can be estimated by measuring air temperature above the cable. The delay variations, which vary slowly with a period of over 10/sup 3/ s, such as annual and daily variations, are clearly correlated for the outgoing and incoming paths. Asymmetry of slow delay variation is below 1 ns (indicated noise deviation). The cause of the delay variation that has a period of 10/sup 0/< tau <102 s is the noise generated by the multiplexing and demultiplexing equipment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Urban multipath propagation delay characteristics in mobile communications

AbstractIn this paper, propagation delay measurements were carried out in Tokyo (metropolitan urban area) where high rises and other buildings are concentrated on a plane and in Kofu (urban area adjacent to mountains) surrounded by tall mountains. The delay characteristics such as delay spread and wave numbers were found.The principal results obtained in these areas are as follows.(1) In a metropolitan urban area, i.e., Tokyo, (a) the average delay spread in a high‐density residential district is less than about 1 μs and the delay profile consists of a group of direct waves arriving directly from the base station; and (b) the average delay spread in a location with high‐rise buildings is also less than 1 μs and the average number of arriving waves is about five with the delay profile consisting of a direct wave group and a reflected wave group from reflecting object.(2) In an urban area adjacent to mountains, i.e., Kofu, the average delay spread is less than about 2 μs and the average number of arriving waves is four. The delay profile consists of a direct wave group and a reflected wave group. The level of the reflected wave group decreases exponentially with the delay time in the case of reflection from buildings, while the level is almost constant within a certain range of delay time and is of a spread shape (rectangular) in the case of reflection from mountains.From these measured results, a simple propagation model consisting of a direct wave group and a reflected wave group is proposed. It is shown that the distance dependence of the delay spread has a peak between the base station and a reflecting object.