Christophe Lallement

Single photon avalanche diodes (SPADs) are crucial for Industry 4.0 advancements, especially in the design of LIght Detection And Ranging (LIDAR) sensors. A compact model is needed to accurately describe their transient behavior. This article presents a lumped model approach that divides the device into different regions. The model accurately emulates the behavior of reach-through SPAD photodiodes by dividing them into high electric field multiplication and low electric field absorption regions. The absorption region can be further subdivided to create multiple possible photon impact points, resulting in precise jitter modeling. This approach enables adaptable and unified SPAD modeling for different avalanche diode architectures. Experimental data confirm the accuracy of the model, and the characterization technique developed highlights the stochastic nature of the device.

Gene regulatory networks exhibiting Boolean behaviour, e.g. AND, OR or XOR, have been routinely designed for years. However, achieving more sophisticated functions, such as control or computation, usually requires sequential circuits or so-called state machines. For such a circuit, outputs depend both on inputs and the current state of the system. Although it is still possible to design such circuits by analogy with digital electronics, some particularities of biology make the task trickier. The impact of two of them, namely the stochasticity of biological processes and the inhomogeneity in the response of regulation mechanisms, are assessed in this paper. Numerical simulations performed in two use cases point out high risks of malfunctions even for designed GRNs functional from a theoretical point of view. Several solutions to improve reliability of such systems are also discussed.

The EKV2.6 MOSFET compact model has had a considerable impact on the academic and industrial community of analog integrated circuit design, since its inception in 1996. The model is available as a free open-source software (FOSS) tool coded in Verilog-A. The present paper provides a short review of foundations of the model and shows its capabilities via characterization and modeling based on a test chip in 180 nm CMOS fabricated via Europractice.

We recently demonstrated the possibility to model and to simulate biological functions using hardware description languages (HDLs) and associated simulators traditionally used for microelectronics. Nevertheless, those languages are not suitable to model and simulate space-dependent systems described by partial differential equations. However, in more and more applications space- and time-dependent models are unavoidable. For this purpose, we investigated a new modeling approach to simulate molecular diffusion on a mesoscopic scale still based on HDL. Our work relies on previous investigations on an electrothermal simulation tool for integrated circuits, and analogies that can be drawn between electronics, thermodynamics, and biology. The tool is composed of four main parts: a simple but efficient mesher that divides space into parallelepipeds (or rectangles in 2D) of adaptable size, a set of interconnected biological models, a SPICE simulator that handles the model and Python scripts that interface the different tools. Simulation results obtained with our tool have been validated on simple cases for which an analytical solution exists and compared with experimental data gathered from literature. Compared with existing approaches, our simulator has three main advantages: a very simple algorithm providing a direct interface between the diffusion model and biological model of each cell, the use of a powerful and widely proven simulation core (SPICE) and the ability to interface biological models with other domains of physics, enabling the study of transdisciplinary systems.

The topic of this paper is the coupling of different tools developed to promote the interface between electronics and biology and its potential for the design of biosensors. More precisely, we put together existing models of electronic devices, a tool (BB-SPICE) that converts descriptions of biological systems into SPICE models and a new tool developed for the compact modeling of biochemical diffusion. This complete virtual prototyping environment is illustrated on an example: a penicillin sensor. Simulations highlight the most critical features that impact the response of the system and can be used to drive designers' choices.

Transconductance efficiency (g _m /I _D ) is an essential design synthesis tool for low-power analog and RF applications. In this paper, the invariance of g _m /I _D versus normalized drain current curve is analyzed in an asymmetric double-gate (DG) fully depleted MOSFET. This paper studies the breakdown of this invariance versus back-gate voltage, transistor length, temperature, drain-to-source voltage, and process variations. The unforeseeable invariance is emphasized by measurements of a commercial 28-nm ultrathin body and box fully depleted Silicon-on-Insulator (SOI) (FDSOI) CMOS technology, thus supporting the g _m /I _D -based design methodologies usage in DG FDSOI transistors sizing.