SPICE Software Research Articles

Experimental study of supercapacitor serial resistance and capacitance variations with temperature

This paper treats an experimental study of the electrical and the thermal behavior of supercapacitors for power electronics and transportation applications. In this study, the charge and discharge of supercapacitors have been characterized by taking into account the temperature variations of the device and its environment. Thermal dependence of supercapacitor serial resistance and capacitance is determined experimentally. An equivalent circuit is proposed to describe the electrical and the thermal behavior of the supercapacitors. The equivalent circuit is implemented in Saber and Spice software for simulations. Experimental and simulation results are presented, analyzed and compared.

A memory/adder model based on single C60molecular transistors

A recent proposal, in which 1-bit memory cells andsimple logic gates such as NOT and NOR gates were based onC60 molecules in an electromechanical grid acting astransistors, is extended to larger architectures. In order tomeet the requirements of standard digital circuit architectures,some modifications have to be made compared to the originalmodel. For example, the number of transistors has to be increasedfrom two to thirteen for a single NOR gate to guarantee balancedlogical levels. In the scheme employed to achieve this in thecurrent work, all two-input gates, namely OR, AND andXOR gates, can be easily constructed using the same concept.These gates are then used to design a 1-bit full-adder and aclocked D-latch, which are then combined with the earlierproposed 1-bit memory cell as the basic constituents of amemory/adder model. Clocked signal transmissions, correspondingto the read process of two 2-bit words from memory cells, theirmovement through registers and finally their addition andpassing the output through another register, are simulated usingthe electrical circuit software SPICE. For the design of thismemory/adder circuit, 464 single C60 transistors are used.

A new global time-domain electromagnetic simulator of microwave circuits including lumped elements based on finite-element method

This paper proposes an extension of the finite-element time-domain method for the global electromagnetic analysis of complex inhomogeneous microwave distributed circuits, containing linear or nonlinear lumped elements. This technique combines Maxwell's equations and circuit equations, directly using SPICE software for the lumped part. Its validation is performed through the study of a strongly coupled two-element active antenna.

Electrical simulation of Thermally Stimulated Depolarization Current Experiments

In this paper we present an electrical model of simulation. This model is used to simulate Thermally Stimulated Depolarization Current measurements. The time constant of the model shows the same temperature behaviour as that observed for amorphous materials. The computations by means of SPICE software give results which are very close to be behaviour laws used in the theory of relaxation in amorphous materials.

Relating the SPICE framework and SEI approach to software process assessment

In June 1993, an international effort (SPICE) was launched to develop a standard for software process assessment. An important goal of this effort is to harmonize existing process assessment approaches. This paper describes and characterizes SEI and SPICE software process assessment work and then highlights the similamties and differences. The following aspects are considered-underlying philosophy, goals, scope/domain, rating processes, underlying reference model, tailorability and impact on the international software community.

Propriétés statiques et dynamiques du transistor MOS de puissance à tranchées (UMOS) “basse-tension”

In this paper~ a contribution to the study of the performances of the trench power MOSFET'S in the low voltage range (< 100 Vi devices is done. A model for the power UMOSFET is presented, based on physical phenomena and electrical properties of the structure. This model is further simplified and embedded in the software SPICE. The comparison of sim- ulated and experimental static and dynamic characteristics allows validation of our approach. We then compare UMOS and VDMOS performance in the same breakdown voltage range: we confirm that the static performances of the UMOS are better than those of the VDMOS. From a dynamic point of view (resistive switching in our case), UMOS offers a smaller chip area than VDMOS for the same losses.

SPICE simulation of lossy and coupled interconnection lines

A new simulation method for analyzing propagation characteristics of high frequency waves on single or coupled lossy interconnections is presented, based on the universal CAD SPICE software. The concept used is the direct analysis of lossy propagating lines as an equivalent circuit which can be easily modeled and simulated by SPICE software. The results obtained in both frequency and time domains agree well with other published methods. The applications to advanced packaging technology, especially for fast IC logic gates and superconductor materials, are promising and offer considerable potential.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

SPICE Model for the Intrinsic Noise of Laser Diodes

A new noise equivalent circuit model of laser diode (LD) is presented in this paper. It enables the noise analysis of LD and its relevant circuit to be complemented in a unified manner using circuit analytical software SPICE and allows the straightforward calculation of the intrinsic shot noise together with modulation response, terminal impedance, transient response and nonlinear distortion. A concept of equivalent input intrinsic shot noise of LD is proposed to establish this model

Power dissipation in frame-transfer charge-coupled devices

The power dissipation for large-area high-speed charge-coupled device (CCD) arrays is analyzed. The four mechanisms responsible for power dissipation in a CCD are carrier lift and friction within the CCD channel, load currents through the on-chip output amplifiers, capacitive charge and discharge currents through the epitaxial layer or substrate, and currents flowing through the polysilicon clock register electrodes. These processes are easily calculated for small or slow devices. For large high-speed devices, on the other hand, the conventional analytical techniques are inadequate. The large device area leads to high resistive-capacitive constants in the parallel clock registers, causing clock pulses to degrade in shape as they travel along a clock electrode. A distributed system analysis based on lumped circuit parameters for each pixel is necessary to calculate the current and thus the power dissipated at each point on the surface of the COD. A computer simulation of a standard frame-transfer CCD was performed using SPICE software. The results of the simulation indicate a much lower power dissipation than previously assumed and also point out various problems with conventional device architectures for large-area high-speed CCDs.

Modelling the capacitance of microstrip line using spice

An original concept for calculating the line capacitance of a microstrip line is presented. An equivalent circuit is created and analysed using the electrical software SPICE; the line capacitance on the inhomogeneous lossless dielectrical layer is deduced by using one impedance–admittance transformation. The numerical results agree well with those of other standard published methods.

Equivalent circuit modelling of lossy coupled lines using spice software

A new skin effect equivalent circuit and a propagation line equivalent circuit for time domain simulation on a single line have been presented in previous work. SPICE simulations have proved the accuracy and efficiency of the proposed method. This concept is extended for coupled line modelling. A dual line device is analysed as a typical example of the usual cases. The method has successfully been extended to N lossy coupled lines. The results show a good agreement with those obtained by other methods.

Computer aided characterization and optimization of the Thumper compression waveform in closed-chest CPR

Optimization of blood flow and blood pressure is critical for a positive outcome of cardiopulmonary resuscitation (CPR). The use of models can facilitate the analysis of different methods of performing CPR. Programming with SPICE software, the authors modified a hardware model electrically equivalent to the human cardiovascular system into a software model to analyze and predict the hemodynamic output parameters of different compression waveform inputs used in thoracic pump CPR. Thumper waveforms produced with the computer model predicted the same decaying frequency response as those found in other studies with humans and a recording manikin in which the generated pressures decreased with increased compression rates from 60 to 140 cycles/min. Using a square-wave input having a flat frequency response, the model predicted a constant diastolic pressure and a steady increase in systolic pressure from 94 to 109 mmHg while increasing compression rate from 60 to 140 cycles/min at a constant 50% duty cycle. Blood flows predicted with the use of a square-wave compression input were greater than the flows predicted with the use of a Thumper waveform, and increased with an increase in compression rate. The model also predicted increased mean systolic pressure when the duty cycle increased from 20% to 80% while diastolic pressure decreased slightly. Although mean systolic pressure increased with increased duty cycle, the model predicted a decrease in coronary flow at the higher duty cycles of all compression waveforms. Increases of 75% to 100% in systolic pressure and blood flow were produced when increases in chest compression force and the rapidity of the rise time, termed spike-impulse CPR, were simulated.