Morgan Madec

Generalization of the Concept of Equivalent Thickness and Capacitance to Multigate MOSFETs Modeling

In this letter, we propose to introduce the notion of equivalent capacitance and to generalize the so-called equivalent-thickness concept to model arbitrary shapes of lightly doped nonplanar multigate MOSFETs, without the need to introduce any unphysical parameter. These definitions, which merely map a multigate geometry into the symmetric double-gate (DG) MOSFET topology, have been validated by extensive comparison with 3-D numerical simulations of quadruple-gate, triple-gate (TG), triangular gate, cylindrical gate-all-around, and DG Fin Field Effect Transistors (FinFETs). Based on this modeling approach, any multigate architecture inherits of the fundamental relationships that have been developed for planar DG MOSFETs, including the normalization of all electrical quantities that considerably simplifies its analysis. In addition, considering a constant mobility, we find that the model can predict electrical characteristics of FinFETs from 275 to 425 K, without the need for any additional parameters. Finally, we were able to predict electrical measurements of a TG MOSFET, making of this generic model an interesting candidate for a design-oriented compact model for arbitrary multigate MOSFETs geometries.

Compact Modeling of a Magnetic Tunnel Junction—Part I: Dynamic Magnetization Model

The potential application range of spintronic devices is wide. However, 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, a dynamic magnetization model inspired from the micromagnetic formalism is presented. This vectorial model is able to describe the quiescent state, as well as the transient behavior of the magnetization vector of an anisotropic single-domain element. The dynamic magnetization model is implemented in VHDL-AMS and requires only eight parameters. Simulation results are also presented and compared with theoretical ones.

Synthetic biology methodology and model refinement based on microelectronic modeling tools and languages.

In microelectronics, the design of new systems is based on a proven time-tested design flow. The goal of this paper is to determine to what extend this design flow can be adapted to biosystem design. The presented methodology is based on a top-down approach and consists of starting with a behavioral description of the system to progressively refine it to its final low-level system representation, composed of DNA parts. To preserve accuracy and simplicity, the design flow relies on refined models of biological mechanisms, which can be expressed by the hardware description languages and simulation tools traditionally used in microelectronics. A case study, the complete modeling of a priority encoder, is presented to demonstrate the effectiveness of the method.

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

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 I-V 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).

Compact modeling of magnetic tunnel junction

A new compact model of a magnetic tunnel junction (MTJ) is presented in this paper. This model is intended to describe the behavior of a MTJ and to take the magnetic as well as the non-linear electronic transport phenomena into account. It should be suitable for circuits simulation and thus, it must be simple (no finite element approach, analytical current versus voltage characteristic only). For this purpose, some assumptions are made. The MTJ model is separated in two entities. The first one concerns the magnetization of a ferromagnetic thin film. The other focuses on the electrical conduction of a MTJ. Both models are implemented and coupled in VHDL-AMS in order to obtain the compact model of a MTJ, which is parameterized with 25 values (19 physical parameters and 6 semi-empirical ones). The first simulations are encouraging. They allow to retrieve classical results on MTJ and to predict interesting behaviors.

Modeling Biology With HDL Languages: A First Step Toward a Genetic Design Automation Tool Inspired From Microelectronics

Nowadays, synthetic biology is a hot research topic. Each day, progresses are made to improve the complexity of artificial biological functions in order to tend to complex biodevices and biosystems. Up to now, these systems are handmade by bioengineers, which require strong technical skills and leads to nonreusable development. Besides, scientific fields that share the same design approach, such as microelectronics, have already overcome several issues and designers succeed in building extremely complex systems with many evolved functions. On the other hand, in systems engineering and more specifically in microelectronics, the development of the domain has been promoted by both the improvement of technological processes and electronic design automation tools. The work presented in this paper paves the way for the adaptation of microelectronics design tools to synthetic biology. Considering the similarities and differences between the synthetic biology and microelectronics, the milestones of this adaptation are described. The first one concerns the modeling of biological mechanisms. To do so, a new formalism is proposed, based on an extension of the generalized Kirchhoff laws to biology. This way, a description of all biological mechanisms can be made with languages widely used in microelectronics. Our approach is therefore successfully validated on specific examples drawn from the literature.

Is SystemC-AMS an appropriate "promoter" for the modeling and simulation of bio-compatible systems?

The paper presents an innovative approach for the modeling and simulation of heterogeneous biological systems based on SystemC-AMS, an open-source C++ extension to the OSCI SystemC Standard. After some basic notions on synthetic biology, an analogy is drawn between this active field of research and nanoelectronics. The paper then presents the SystemC-AMS Timed DataFlow (TDF) modeling formalism used to model these multidomain devices. It also details the presented case study, a bio-compatible system with feedback consisting of a biological sensor instanciating a T flip-flop BioBrick and a EnFET, a voluntarily simple digital processing unit and an actuator based on the Hodgkin-Huxley neuron model. Some simulation results are given that validate the use of SystemC-AMS as an attractive, open-source and flexible framework for modeling complex bio-compatible systems.

Assessment of the spinning-current efficiency in cancelling the 1/f noise of Vertical Hall Devices through accurate FEM modeling

The Vertical Hall Device integrable in a shallow N-well, and thus compatible with Low-Voltage CMOS processes, i.e. the LV-VHD, was proposed five years ago. Its layout is similar to the layout of the HV-VHD, i.e. the conventional 5-contact VHD integrated in the deep N-well of High-Voltage processes. However, in the LV-VHD, the Hall voltage is picked-up from the external contacts while it is picked-up from the internal contacts in the HV-VHD. Such sensing schemes make not obvious the application of the well-known Spinning-Current Technique (SCT) used in Horizontal Hall Device (HHD) for offset and 1/f noise attenuation. In this paper, an accurate Finite Element Modeling (FEM) analysis of the SCT for VH-Devices is presented. All the second-order effects which influence the VHD, i.e. the Junction Field Effect (JFE) and the Carrier Velocity Saturation (CVS), are taken into account. Simulation results carried out on a LV-VHD show that SCT remains efficient even under high current biasing, i.e. when CVS takes place.

An improved compact model of cross-shaped horizontal CMOS-integrated Hall-effect sensor

A new compact model of a cross-shaped horizontal integrated Hall-effect sensor is presented in this paper. Compared to existing models, the model reliability is improved, especially for designs in which the bias and the measurement circuits are not independent. The Hall device model uses six subcomponents, each modeling the non-linear resistance due to the sensor space charge region modulation and the Hall voltage. The model is implemented in VHDL-AMS and Verilog-A. It includes 10 parameters (physical parameters of the semiconductor and sensor geometry). The model gives simulation results that are in accordance with classic experimental results founded in the literature.

Using digital electronic design flow to create a Genetic Design Automation tool

Synthetic bio-systems become increasingly more complex and their development is lengthy and expensive. In the same way, in microelectronics, the design process of very complex circuits has benefited from many years of experience. It is now partly automated through Electronic Design Automation tools. Both areas present analogies that can be used to create a Genetic Design Automation tool inspired from EDA tools used in digital electronics. This tool would allow moving away from a totally manual design of bio-systems to assisted conception. This ambitious project is presented in this paper, with a deep focus on the tool that automatically generates models of bio-systems directly usable in electronic simulators.