Analog Hardware Description Language Research Articles

Six Transistor Carbon Nanotube Field Effect Transistors Based RAM Design and Hardware Description Language Code Development

The goal of this thesis is to develop carbon nanotube field effect transistors (CNFETs) based static random-access memory (SRAM) and implement it into a Very-highspeed integrated circuit Hardware Description Language Analog and Mixed-Signal (VHDLAMS). To achieve this objective, a compact model of the transistor known as enhancementmode MOSFET-like SWCNT-CNFET is used. This circuit-compatible model of CNFET is described using VHDL-AMS and tested for basic electrical characteristics. This model is valid for CNFETs with channel lengths greater than 20 nm. Based on the CNFETs a new SRAM is designed, and implemented in VHDL-AMS. The performance of the proposed SRAM cell is investigated and compared with SRAMs from conventional metal-oxide semiconductor field effect transistors (MOSFETs). The effect of substrate biasing a CNFET is also demonstrated and implemented in designing the SRAM cell. The VHDL-AMS codes of the CNFET and the SRAM are simulated in software known as Ansoft Simplorer. The compact model of the CNFET is organized hierarchically in three main levels. The first level models the intrinsic channel just beneath the gate of the transistor. The second level builds upon the first level and models the doped source and drain regions of the CNFET. The last level represents the complete trans-capacitance model of the transistor and accounts for multiple CNTs. The proposed SRAM cell is composed of four CNFETs and two load resistors. The driver CNFETs of the proposed SRAM cell are substrate biased. Besides, 8-bit complete SRAM architecture based on this cell is indicated. The performance analysis of the SRAM shows that it has better writing and reading speed as well as better stability when compared with SRAM from conventional MOSFETs. Specifically, the newly proposed SRAM cell has read time of twenty five pico seconds, write time of twenty pico seconds and can tolerate a noise of 120 mV at 32 nm node technology.

A Comprehensive High-Level Model for CMOS-MEMS Resonators

This paper presents a behavioral modeling technique for CMOS microelectromechanical systems (MEMS) microresonators that enables simulation of an MEMS resonator model in Analog Hardware Description Language format within a system-level circuit simulation. A 100-kHz CMOS-MEMS resonant pressure sensor has been modeled into Verilog-A code and successfully simulated within Cadence framework. Analysis has shown that simulation results of the reported model are in agreement with the device characterization results. As an application of the proposed methodology, simulation and results of the model together with an integrated monolithic low-noise amplifier is exemplified for detecting the position change of the resonator.

Nonlinear cc-beam microresonator model for system level electrical simulations: Application to bistable behavior analysis

Microelectromechanical resonators nonlinearities can be exploited in many ways to obtain a set of diverse new applications. In particular, some applications of bistable behavior includes threshold mechanical switches, memory cells, energy harvesting and chaotic signal generators. A key step for practical and efficient design for bistability behavior involves accounting for accurate and efficient models. In this paper we present a nonlinear electromechanical model for capacitive clamped-clamped beam resonators implemented in an analog hardware description language (AHDL) enabling system level electrical simulations. The model accounts for nonlinearities from variable resonator-electrode gap, residual fabrication stress, fringing field contributions as well as an accurate resonator deflection profile in contrast to parallel plate approximations. The model has been applied to derive for first time accurate analytical expressions for bistability design conditions. The work includes FEM analysis and experimental data that corroborates the correctness of the model in describing the required bias voltage conditions for bistability.

Physical Model of Pixels in Twisted Nematic Active-Matrix Liquid Crystal Displays

In this paper, we propose a new physical model to predict the transient responses of an active-matrix liquid crystal display (LCD) in a twisted nematic (TN) mode. For the behavioral model, three types of data are most important: 1) capacitance–voltage; 2) transmittance–voltage characteristics; and 3) time constant parameters $a_{1}$ and $a_{2}$ . We extract them from the physical properties of TN LC molecules, such as dielectric anisotropy, birefringence, viscosity, cell gap, and elastic constant. We describe the behavior of the TN-LCD by using the analog hardware description language, Verilog-A. We simulate optically rising responses of the TN-LCD panel by importing the behavioral circuit model in the circuit simulator. The simulation results show that the transient optical responses show excellent matches with the measurement ones. In addition, we can observe how the behaviors of optical responses change with varying the physical parameters, such as cell gap, dielectric anisotropy, and elastic constant.

Behavioral Circuit Models of Stereoscopic 3-D Liquid Crystal Displays and Shutter Glasses

In this paper, behavioral circuit models of a stereoscopic 3-D liquid crystal display (LCD) and shutter glasses (SGs) are proposed. Until now, no study has been conducted on a model that can demonstrate the optical behavior of a 3-D LCD panel, because it includes black frame insertion. In addition, a circuit model of SGs should be established to completely illustrate the behavior of a stereoscopic 3-D LCD system. These circuit models can accurately predict the optical responses of dynamic transitions in 3-D LCD systems and those of SGs. We can then develop a complete behavioral model of the stereoscopic 3-D LCD system by combining the behavioral models of both the 3-D LCD panel and SGs. SmartSPICE simulations are performed to verify our model, which is implemented by an analog hardware description language, Verilog-A. On the basis of these simulation and measurement results, we can conclude that the proposed behavioral circuit models can accurately describe the optical responses of combined displays such as stereoscopic 3-D LCDs.

Behavioral Model of Patterned Vertical Alignment Pixel in Active-Matrix Liquid Crystal Displays

This paper proposes a more accurate behavioral circuit model to predict transient responses of an active-matrix liquid crystal display (AMLCD) with a patterned vertical alignment (PVA) mode. In the case of the PVA mode, we observed that simulation errors increase when the conventional circuit model is directly applied to overdriven static and dynamic data transitions. To overcome this issue, we investigate the actual behavior of the liquid crystal (LC) molecules in the PVA AMLCD pixel using a high-speed camera attached to a microscope. We discovered that the behavior of the LC molecules is significantly dependent on their proximity to the edges of transparent electrodes. Based on this investigation, we propose a first-order circuit model that has two LC groups with two different response characteristics. The proposed model is embedded in a circuit simulator using an analog hardware description language. Simulation results show that the transient optical responses are considerably more accurate than the conventional responses for any data transitions, including overdriven transitions.

Magnetic Components Dynamic Modeling With Thermal Coupling for Circuit Simulators

This paper proposes a nonlinear dynamic model of magnetic components for use in circuit simulators. It includes the material's nonlinear hysteresis behavior with accurate modeling of winding and core losses in addition to thermal effects that are not considered by existing models. The model is based on the principle of separation of static and dynamic contributions as well as Bertotti's theory. Very high speed integrated circuits hardware description language-analog and mixed signals is used as a modeling language due to its multi-domain modeling feature, allowing coupling with a thermal model. The thermal model is represented by a temperature source for static thermal conditions or by an equivalent thermal circuit for self-heating conditions. The magnetic component model is implemented in circuit simulation software SIMPLORER and validated by modeling a nanocrystalline-core inductor. The effects of frequency, temperature, and waveform are studied.

VHDL-AMS Electromagnetic Automatic Modeling for System Simulation and Design

To improve interoperability between system-level modeling and simulation, this paper proposes an approach to export models from dedicated magnetic tools into a standardized format, such as Very-high-speed integrated circuits Hardware Description Language-Analog and Mixed Signal (VHDL-AMS), as a powerful modeling language. The goal is to let designers use a unique modeling approach and single simulation tool to simulate the behavior of a complete electromagnetic system and to make the translation of existing models to VHDL-AMS easy. Thus they can reduce the investment. This paper addresses this methodology as a computer-aided generation of the VHDL-AMS code from macro and micro electromagnetic devices for system simulation. The translation uses model-driven engineering methods for the transformation of one model to another and the code generation from models. Implementation and methodology are illustrated on a dynamic E-shaped actuator as a macro-system case study and a diamagnetic levitation device as micro-system one.

MPPT System for Photovoltaic Module Connected to Battery Adapted for Unstable Atmospheric Conditions Using VHDL-AMS

This paper presents a novel maximum power point tracking (MPPT) algorithm used in photovoltaic (PV) module connected to a storage battery. The main aim of this algorithm is to maximize the PV array output power by tracking continuously the maximum power point (MPP) which depends on atmospheric conditions (panel temperature and irradiance). The full system is composed of a PV array, a storage battery and an electronic boost-type DC–DC converter inserted between the PV array and the storage battery. The proposed MPPT control algorithm used to control the boost DC–DC converter is intended to lead the PV array power to its maximum point by keeping the PV array voltage stable with little deviation. The modeling of this system is realized using the novel concept of “functional prototyping” based on Very high speed integrated circuits Hardware Description language–Analog and Mixed Signal (VHDL-AMS) which can be particularly useful to design and redesign complex system with multi-technologic aspect, and to optimize strategies of control. The usefulness of the proposed MPPT algorithm has been fully verified by digital simulation using Simplorer software, where the obtained results show that the proposed MPPT method can improve PV power system performances noticeably in steady and dynamic states.

Behavioral Circuit Model of Active-Matrix Liquid Crystal Display With Charge-Shared Pixel Structure

This paper proposes a behavioral circuit model to precisely predict optical responses of an active-matrix liquid crystal (LC) display with charge-shared vertical alignment (CS-VA) mode. CS-VA mode consists of two subpixels in one pixel to mitigate the off-axis gamma distortion. We present a new method using overdrive voltages to obtain accurate capacitance versus voltage (C-V) characteristics in CS-VA mode. In addition, we present a new technique to obtain transmittance versus voltage (T-V) characteristics of the two subpixels by using a high-speed camera with image processing. In addition, we analyze the panel to obtain precise voltage levels after sharing charges. We describe the behavior of the CS-VA LC display (LCD) by using an analog hardware description language, Verilog-A, and we simulate the CS-VA LCD panel by importing the behavioral circuit model in a circuit simulator, Smart-SPICE. The simulation results of the transient optical responses show excellent matches with the measurement ones.

Precise prediction of optical responses of all types of liquid crystal displays by behavioral models

AbstractWe propose a behavioral circuit model to estimate transient optical responses of an active‐matrix liquid crystal display (AMLCD). We apply it to twisted‐nematic, patterned vertical alignment, and in‐plane switching AMLCDs to verify our model's universality. To obtain more accurate simulation results, we propose a method to obtain the capacitance–voltage data from natural optical responses. We describe the behavior of all types of AMLCDs by using an analog hardware description language, Verilog‐A. We simulate the AMLCD panels by importing the behavioral circuit model in a circuit simulator, Smart‐SPICE. The simulation results of the transient optical responses were almost identical to the measurement ones regardless of liquid crystal modes.

A Behavioral Circuit Model of Active-Matrix Liquid Crystal Displays for Optical Response Simulation

We propose a behavioral circuit model to precisely predict optical responses of an active-matrix liquid crystal (LC) display (LCD) using a patterned vertical alignment (PVA) mode. To get more accurate simulation results, we propose two LC groups with different time constants for a pixel after observing the LCD pixels by using a high-speed camera. In addition, we include a time-delay concept into our behavioral model for brightening or rising transitions. We describe the behavior of the PVA-LCD by using the analog hardware description language Verilog-A. We simulate the PVA-LCD panel by importing the behavioral circuit model in the circuit simulator SmartSPICE. The simulation results of the transient optical responses show excellent matches with the measurement ones.

A Microscopy Technique based on Bio-impedance Sensors

It is proposed a microscopy for cell culture applications based on impedance sensors. The imagined signals are measured with the Electrical Cell-Substrate Spectroscopy (ECIS) technique, by identifying the cell area. The proposed microscopy allows real-time monitoring inside the incubator, reducing the contamination risk by human manipulation. It requires specific circuits for impedance measurements, a two-dimensional sensor array (pixels), and employing electrical models to decode efficiently the measured signals. Analogue Hardware Description Language (AHDL) circuits for cell-microelectrode enables the use of geometrical and technological data into the system design flow. A study case with 8x8 sensor array is reported, illustrating the evolution and power of the proposed image acquisition.

Compact Modeling of a Magnetic Tunnel Junction—Part II: Tunneling Current Model

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The potential application range of spintronic devices is wide. However, a few works were carried out in the field of compact modeling of such devices. The lack of compact models dramatically increases the design complexity of circuits using spintronic devices. In this paper, focus is made on magnetic tunnel junctions (MTJs). It is presented in a set of two papers: The first part deals with the magnetic aspects of the MTJ, whereas the second one covers the electrical aspects. In this part, the tunneling conduction across the MTJ is modeled using an analytical <formula formulatype="inline"><tex Notation="TeX">$I$</tex></formula>–<formula formulatype="inline"><tex Notation="TeX">$V$</tex></formula> equation, which is based on previous works on this topic and involves some assumptions that are discussed. The complete compact model is implemented in a very high speed integrated circuit (VHSIC) hardware description language analog mixed signal and includes magnetization aspects presented in the first part. The model requires 25 parameters (19 physical and 6 semiempirical parameters). </para>

Cell layer level generalized dynamic modeling of a PEMFC stack using VHDL-AMS language

A generalized, cell layer scale proton exchange membrane fuel cell (PEMFC) stack dynamic model is presented using VHDL-AMS (IEEE standard Very High Speed Integrated Circuit Hardware Description Language-Analog and Mixed-Signal Extensions) modeling language. A PEMFC stack system is a complex energy conversion system that covers three main energy domains: electrical, fluidic and thermal. The first part of this work shows the performance and the advantages of VHDL-AMS language when modeling such a complex system. Then, using the VHDL-AMS modeling standards, an electrical domain model, a fluidic domain model and a thermal domain model of the PEMFC stack are coupled and presented together. Thus, a complete coupled multi-domain fuel cell stack 1-D dynamic model is given. The simulation results are then compared with a Ballard 1.2 kW NEXA fuel cell system, and show a great agreement between the simulation and experimentation. This complex multi-domain VHDL-AMS stack model can be used for a model based control design or a Hardware-In-the-Loop application.

Methodology to Predict EME Effects in CAN Bus Systems Using VHDL-AMS

The electromagnetic emissions (EME) of integrated circuits (ICs) are of increasing importance in the selection of automotive components. Although the IC is treated as the main cause for these emissions, the electrical environment, i.e., the application of an IC including the minimal circuitry on the application board and its layout, as well as the global connection terminals (i.e., supply pins and bus signals) representing the load of an IC are crucial in determining the emission behavior of the entire system. This paper provides application engineers information about different aspects related to the EME of a controller area network (CAN) bus system and how emissions are generated and transformed within the application environment. It presents a methodology to investigate and predict the effects by using Very High-Speed IC Hardware Description Language-Analog Mixed Signal (VHDL-AMS). The description focuses on the interaction between the CAN transceivers and the twisted pair transmission line connecting them. Both common mode and differential mode as well as mode conversion aspects are considered. It highlights the fact that EMEs from a CAN bus system highly depend on the application environment.

Modelling of fuel cells using multi-domain VHDL-AMS language

This study presents a IEEE standard Very High Speed Integrated Circuit Hardware Description Language-Analog and Mixed-Signal Extension (VHDL-AMS) modelling of a complex multi-domain energy conversion system: a fuel cell stack. A comparative study between the different modelling approaches (bond graphs, electrical equivalent circuits) is given to show the great advantages of the VHDL-AMS language in the design process of fuel cell systems. The modelling approach allows the design team to split the work into several parts (concurrent engineering) and validate each part independently. The fuel cell stack model fits the experimental results. It is able to predict the voltage and the power of the fuel cell with a good accuracy taking into account the water content of the membrane. This last point is really important to design the air supply system (compressor and humidifier) and its associated control.

Ultrasonic Piezoceramic Transducer Modeling With VHDL-AMS: Application to Ultrasound Nonlinear Parameter Simulations

This paper presents an ultrasonic transducer modeling with very high-speed integrated circuit (VHSIC) hardware description language-analog and mixed signal (VHDL-AMS) IEEE 1076.1 integrated in a global measurement cell modeling dedicated to biological tissue ultrasound characterization. Usual modeling of ultrasonic transducers is based on electrical analogy and is not simulated in the global measurement environment. The ultrasonic transducer modeling proposed is simulated with a nonlinear acoustic load and electronic excitation. The nonlinear B/A parameter is used to characterize a medium with a comparative method. The measurement cell is composed of two piezoelectric ceramic transducers, which are implemented with Redwood's electric scheme. The analyzed medium is placed between the transducers and modeled to take into account the nonlinear propagation with the B/A parameter. The usual transmission line model has been modified to take into account the nonlinear propagation for a one-dimensional (1-D) wave. Simulations of the transducer pulse response and electrical impedance show a VHDL-AMS model that is in good agreement with measurement and compared to the usual personal computer simulation program with integrated circuit emphasis results simulations. Results obtained by simulation of mediums (blood, milk, liver, and human fat tissue) showed good agreement between modeling and experimental measurement, and a maximum error of about 12.5% for B/A measurement-simulation

Analyzing continuous-time /spl Delta//spl Sigma/ Modulators with generic behavioral models

In a generic behavioral model of an analog or mixed-signal electronic system, the internal and external signals and their interactions are formulated by more general descriptions than in commonly used behavioral models. This allows a more flexible design methodology. Whereas a behavioral model models an architecture of a system at a specific abstraction level, a generic behavioral model is built up out of generic functions that by specialization of these functions allows the modeling of a wide range of system architectures with different degrees of modeling accuracy. This enhanced abstraction level makes the approach suited for systematic analysis through refinement and architectural exploration of analog and mixed-signal building blocks and systems using computer-aided-design tools. As an application of this methodology, a generic behavioral model has been developed for continuous-time (CT) /spl Delta//spl Sigma/ analog-to-digital converters (ADCs) together with the specialization functions to take into account all major nonidealities at different levels of detail, including effects like jitter, saturation, and weakly nonlinear distortion. The results of experiments of a SystemC implementation of the model are presented. Compared to other models for analysis, the proposed method enables high accuracy even at low abstraction levels, whereas the event-driven character of the model results in short simulation times compared to time-marching simulations of behavioral models, written for example in very-high-speed-integrated-circuit (VHSIC) Hardware Description Language Analog and Mixed Signal (VHDL-AMS) or Matlab/Simulink. The flexibility of the model is demonstrated.

Behavioural modelling and system-level simulation of micromechanical beam resonators

This paper presents a behavioural modelling technique for micromechanical beam resonators that enables the simulation of MEMS resonator model in Analog Hardware Description Language (AHDL) format within a system-level circuit simulation. A 1.13 MHz clamped-clamped beam and a 10.4 MHz free-free beam resonators have been modelled into Verilog-A code and successfully simulated with Spectre in Cadence. Analysis has shown that both models behave well and their electrical characteristics are in agreement with the theory.