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In this work, a CMOS transistor array is presented, which allows performing process variability, Random Telegraph Noise and BTI/CHC aging characterization in a single chip. The array, called ENDURANCE, integrates 3136 MOS transistors, for single and massive electrical testing. This chip, together with a dedicated measurement set-up, allows programming any of these electrical tests, considerably reducing...
This paper presents a toolbox for the automation of the electrical characterization of CMOS transistors. The developed software provides a user-friendly interface to carry out different tests to evaluate time-zero (i.e., process) and time-dependent variability in CMOS devices. Also, the software incorporates a post-processing capability that allows users to visualize the data. Moreover, without loss...
This paper presents new indexing and mutation operators, in the context of bottom-up hierarchical multi-objective optimization of radio frequency integrated circuits, for pre-optimized sets of solutions from the hierarchical sub-levels when moving up in hierarchy. Two ideas, one based on a Voronoi decomposition and another based on the nearest neighborhood, are explored, where, and unlike previous...
The availability and efficiency of reliability simulators for analog ICs is becoming critical with the scaling of devices down to the nanometer nodes. Two of the main challenges here are how to simultaneously include different sources of unreliability (such as the time-zero or spatial variability and the aging or time-dependent variability), and how to account for the self-induced changes in device...
In this paper, the major methodologies proposed in the last years to speed-up the synthesis of radio-frequency integrated circuits blocks are overviewed. The challenges to automate this task are discussed, and, to avoid non-systematic iterations between circuit and layout design steps, the architecture of an innovative solution is proposed. The proposed tool exploits the full capabilities of most...
This paper focuses on the systematic design of voltage controlled oscillators (V CO), a commonly used radiofrequency (RF) electronic circuit. RF circuits are among the most difficult analog circuits to design due to its trade-offs and high operation frequencies. At such operation frequencies, layout parasitics and accurate passive component characterization become of upmost importance, causing re-design...
This paper describes a class of real-life optimization problems that has not been addressed before: a multi-objective optimization in which one objective is neither minimized nor maximized but uniformly swept over a wide range. The limitations of conventional multi-objective optimization algorithms to deal with this kind of problems are illustrated via the optimization of radiofrequency inductors...
With the evolution in the scale of integration in ICs, aging-related problems are becoming more important and, nowadays, solutions to cope with these issues are not yet mature enough, especially in the field of analog circuit simulation. CASE, the novel simulator presented in this paper, can evaluate the impact of reliability effects in analog circuits through a stochastic physic-based model. The...
Variability is one of the main and critical challenges introduced by the continuous scaling in integrated technologies and the need for reliable ICs. In this regard, it is necessary to take into account time-zero (i.e., spatial or process variability) and time-dependent variability (i.e., aging). While process variability has been extensively treated, considerable efforts are currently being made...
The use of electromagnetic simulations is crucial in radiofrequency and microwave circuits since accurate estimations of parasitics and performances are essential. In addition, design methodologies based on optimization algorithms have been used in order to design such circuits, while efficiently exploring its design trade-offs. However, due to the high computational cost, optimization-based methodologies...
The dependence of the MOSFET threshold voltage variability on device geometry (width (W) and length (L)) has been studied from experimental data. Our results evidence, in agreement with other works, deviations from the Pelgrom's rule, especially in smaller technologies. TCAD simulations were also performed which further support the experimental data and provide physical information regarding the origin...
Integrated inductors are one of the most important passive elements in radio frequency design, due to their wide usage in wireless communication circuits. Typically, electromagnetic simulators are used in order to estimate the inductors performance with high accuracy as a function of the inductor geometrical and electrical parameters. Such simulations offer high-accuracy, but are computationally expensive...
This paper presents SIDe-O, a CAD tool developed for the design and optimization of integrated inductors based on surrogate modeling techniques. This tool provides a solution to the problem of accurately and efficiently optimizing the design of inductors. The models used present less than 1% error when compared to EM simulations while reducing the simulation time by several orders of magnitude. Additionally,...
Passive components play a key role on the design of RF CMOS integrated circuits. Their synthesis, however, is still an unsolved problem due to the lack of accurate analytical models that can replace the computationally expensive electromagnetic simulations (EM). Both, physical-based and surrogate models have been reported that fail to accurately model the complete design space of inductors. Surrogate-assisted...
Pareto fronts of circuits whose performance depend on other circuits that they are connected to must be updated for each interconnection conditions. This paper reports, for the first time, the conditions for which a transformation without loss of information is guaranteed.
Reliability has become a critical challenge in integrated circuit design in today's CMOS technologies. Aging problems have been added to the well-known issues due to spatial variations that are caused by imperfections in the fabrication process. In this sense, transistor wear-out phenomena such as Bias Temperature Instability (BTI) and Hot Carriers (HC) cause a time-dependent variability that is added...
Integrated inductors are one of the most important passive elements in RF circuits. However, time-consuming simulations, such as electromagnetic simulations, have to be used to evaluate their performances with high accuracy. In order to overcome this problem, analytical models can be used. In this paper, a surrogate model based on Kriging functions is presented that accurately predicts the performance...
The accuracy of high-frequency models of passive RF devices, e.g., inductors or transformers, presents one of the most challenging problems for RF integrated circuits. Accuracy limitations lead RF designers to time-consuming iterations with electromagnetic simulators. This paper will explore and compare two advanced modeling techniques. The first one is based on the segmented model approach, in which...
Bottom-up synthesis approaches based on the hierarchical composition of performance models have been proposed as a promising alternative to conventional top-down hierarchical synthesis approaches. This paper discusses problems related to the context-dependence of performance models and proposes possible solutions. Techniques for the composition of multi-dimensional performance models so that the efficiency...
Emerging hierarchical design methodologies based on the use of Pareto-optimal fronts (PoFs) are promising candidates to reduce the bottleneck in the design of analog circuits. However, little work has been reported about how to transmit the information provided by the PoFs of low hierarchical level blocks through the hierarchy to compose the performance models of higher-level blocks. This composition...
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