International audienceThis paper examines aspects of design technology required to explore advanced logic-circuit design using carbon nanotube field-effect transistor (CNTFET) devices. An overview of current types of CNTFETs is given and highlights the salient characteristics of each. Compact modeling issues are addressed and new models are proposed implementing: 1) a physics-based calculation of energy conduction sub-band minima to allow a realistic analysis of the impact of CNT helicity and radius on the dc characteristics; 2) descriptions of ambipolar behavior in Schottky-barrier CNTFETs and ambivalence in double-gate CNTFETs (DG-CNTFETs). Using the available models, the influence of the parameters on the device characteristics were simulated and analyzed. The exploitation of properties specific to CNTFETs to build functions inaccessible to MOSFETs is also described, particularly with respect to the use of DG-CNTFETs in fine-grain reconfigurable logic
Abstract-This paper focuses on commonalities and differences between the two mixed-signal hardware description languages VHDL-AMS and Verilog-AMS in the case of modeling heterogeneous or multi-discipline systems. The paper has two objectives. The first one consists of modeling the structure and the behavior of an airbag system using both the VHDL-AMS and the Verilog-AMS languages. Such a system encompasses several time abstractions (i.e. discrete-time and continuous-time), several disciplines, or energy domains (i.e., electrical, thermal, optical, mechanical, and chemical), and several continuous-time description formalisms (i.e., conservative-law and signal-flow descriptions). The second objective is to discuss the results of the proposed modeling process in terms of the descriptive capabilities of the VHDL-AMS and Verilog-AMS languages and of the generated simulation results. The tools used are Advance-MS from Mentor Graphics for VHDL-AMS and AMS Simulator from Cadence Design Systems for Verilog-AMS. The paper shows that both languages offer effective means to describe and simulate multi-discipline systems, although using different descriptive approaches. It also highlights current tool limitations since full language definitions are not yet supported.
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