Simulations and comparisons of basic analog and digital circuit blocks employing Tunnel FETs and conventional FinFETs

NTRODUCTION \u2015 In the past decade the Tunnel Field Effect Transistor (TFET) relying on band-to-band tunneling (BTBT) has emerged as one of the most promising small slope FETs able to achieve a subthreshold swing (SS) below the room temperature 60 mV/dec limit of conventional MOSFET [1]. Many simulation studies attributed to TFETs the potential to outperform conventional MOSFETs in the ultra-low voltage domain (VDD < 0.4 V) in both analog [2-3] and digital [4-7] applications. However, only basic digital and analog circuits have been fabricated up to date, such as current mirrors [8] and inverter gates [9]. As for semiconductor materials, III-V hetero-structure TFETs may be able to achieve a sub-thermal SS in a wide current range and, at the same time, very competitive on currents [1], as demonstrated by a recently fabricated vertical InAs/GaAsSb/GaSb nanowire n-type TFETs [10]. The aim of this work is to benchmark a complementary III-V TFET technology platform against the mainstream FinFET reference, by considering basic building blocks of digital and analog applications. To this purpose, we selected a complementary III-V TFET technology platform designed and optimized using full quantum simulations in [11], where n- and p-type TFET pairs are realized in the same InAs/AlGaSb material system. The use of such devices allowed us to remove the excessively optimistic assumption of perfectly symmetric n- and p-type TFETs, very frequently embraced in previous simulation studies (e.g. in [2, 7]). We present circuit-level simulations performed on current mirrors and inverter-based logic blocks, which are identified as basic topologies representative of the analog and digital design realms, respectively. Similar benchmarking results for the same technology platforms have been obtained by focusing the comparison on more complicated circuit blocks [3], [5] and [6]

Assessment of InAs/AlGaSb Tunnel-FET Virtual Technology Platform for Low-Power Digital Circuits

In this work, a complementary InAs/Al0.05Ga0.95Sb tunnel field-effect-Transistor (TFET) virtual technology platform is benchmarked against the projection to the CMOS FinFET 10-nm node, by means of device and basic circuit simulations. The comparison is performed in the ultralow voltage regime (below 500 mV), where the proposed III-V TFETs feature ON-current levels comparable to scaled FinFETs, for the same low-operating-power OFF-current. Due to the asymmetrical n-and p-Type I-V exts , trends of noise margins and performances are investigated for different Wp/Wn ratios. Implications of the device threshold voltage variability, which turned out to be dramatic for steep slope TFETs, are also addressed

Digital and analog TFET circuits: Design and benchmark

In this work, we investigate by means of simulations the performance of basic digital, analog, and mixed-signal circuits employing tunnel-FETs (TFETs). The analysis reviews and complements our previous papers on these topics. By considering the same devices for all the analysis, we are able to draw consistent conclusions for a wide variety of circuits. A virtual complementary TFET technology consisting of III-V heterojunction nanowires is considered. Technology Computer Aided Design (TCAD) models are calibrated against the results of advanced full-quantum simulation tools and then used to generate look-up-tables suited for circuit simulations. The virtual complementary TFET technology is benchmarked against predictive technology models (PTM) of complementary silicon FinFETs for the 10 nm node over a wide range of supply voltages (VDD) in the sub-threshold voltage domain considering the same footprint between the vertical TFETs and the lateral FinFETs and the same static power. In spite of the asymmetry between p- and n-type transistors, the results show clear advantages of TFET technology over FinFET for VDDlower than 0.4 V. Moreover, we highlight how differences in the I-V characteristics of FinFETs and TFETs suggest to adapt the circuit topologies used to implement basic digital and analog blocks with respect to the most common CMOS solutions

Unraveling population trends in Italy (1921–2021) with spatial econometrics

Testing density-dependence and path-dependence in long-term population dynamics under differentiated local contexts contributes to delineate the changing role of socioeconomic forces at the base of regional disparities. Despite a millenary settlement history, such issue has been rarely investigated in Europe, and especially in highly divided countries such as those in the Mediterranean region. Using econometric modeling to manage spatial heterogeneity, our study verifies the role of selected drivers of population growth at ten times between 1921 and 2021 in more than 8000 Italian municipalities verifying density-dependent and path-dependent dynamics. Results of global and quantile (spatial) regressions highlight a differential impact of density and (lagged) population growth on demographic dynamics along the urban cycle in Italy. Being weakly significant in the inter-war period (1921-1951), econometric models totalized a high goodness-of-fit in correspondence with compact urbanization (1951-1981). Model's fit declined in the following decades (1981-2021) reflecting suburbanization and counter-urbanization. Density-dependence and path-dependence were found significant and, respectively, positive or negative, with compact urbanization, and much less intense with suburbanization and counter-urbanization. A spatial econometric investigation of density-dependent and path-dependent mechanisms of population dynamics provided an original explanation of metropolitan cycles, delineating the evolution of socioeconomic (local) systems along the urban-rural gradient

Digital and analog TFET circuits: Design and benchmark

In this work, we investigate by means of simulations the performance of basic digital, analog, and mixed-signal circuits employing tunnel-FETs (TFETs). The analysis reviews and complements our previous papers on these topics. By considering the same devices for all the analysis, we are able to draw consistent conclusions for a wide variety of circuits. A virtual complementary TFET technology consisting of III-V heterojunction nanowires is considered. Technology Computer Aided Design (TCAD) models are calibrated against the results of advanced full-quantum simulation tools and then used to generate look-up-tables suited for circuit simulations. The virtual complementary TFET technology is benchmarked against predictive technology models (PTM) of complementary silicon FinFETs for the 10 nm node over a wide range of supply voltages (VDD) in the sub-threshold voltage domain considering the same footprint between the vertical TFETs and the lateral FinFETs and the same static power. In spite of the asymmetry between p- and n-type transistors, the results show clear advantages of TFET technology over FinFET for VDDlower than 0.4 V. Moreover, we highlight how differences in the I-V characteristics of FinFETs and TFETs suggest to adapt the circuit topologies used to implement basic digital and analog blocks with respect to the most common CMOS solutions

Impact of TFET unidirectionality and ambipolarity on the performance of 6T SRAM cells

We use mixed device-circuit simulations to predict the performance of 6T static RAM (SRAM) cells implemented with tunnel-FETs (TFETs). Idealized template devices are used to assess the impact of device unidirectionality, which is inherent to TFETs and identify the most promising configuration for the access transistors. The same template devices are used to investigate the $ extV- m DD range, where TFETs may be advantageous compared to conventional CMOS. The impact of device ambipolarity on SRAM operation is also analyzed. Realistic device templates extracted from experimental data of fabricated state-of-the-art silicon pTFET are then used to estimate the performance gap between the simulation of idealized TFETs and the best experimental implementations

Microscopic origin of random telegraph noise fluctuations in aggressively scaled RRAM and its impact on read disturb variability

Random telegraph noise (RTN) is an important intrinsic phenomenon of any logic or memory device that is indicative of the reliability and stochastic variability in its performance. In the context of the resistive random access memory (RRAM), RTN becomes a key criterion that determines the read disturb immunity and memory window between the low (LRS) and high resistance states (HRS). With the drive towards ultra-low power memory (low reset current) and aggressive scaling to 10 × 10 nm2 area, contribution of RTN is significantly enhanced by every trap (vacancy) in the dielectric. The underlying mechanisms governing RTN in RRAM are yet to be fully understood. In this study, we aim to decode the role of conductance fluctuations caused by oxygen vacancy transport and inelastic electron trapping and detrapping processes. The influence of resistance state (LRS, shallow and deep HRS), reset depth and reset stop voltage (VRESET-STOP) on the conductance variability is also investigated. © 2013 IEEE

Changes of intracardiac flow dynamics measured by HyperDoppler in patients with aortic stenosis

Aims Assessment of intracardiac flow dynamics has recently acquired significance due to the development of new measurement methods based on echocardiography. Recent studies have demonstrated that cardiac abnormalities are associated with changes in intracardiac vortical flows. Yet, no previous study assessed the impact of aortic stenosis (AS) on intracardiac vortices. This study aims to explore the clinical potential of additional information provided by quantifying intracardiac flow dynamics in patients with AS. Methods and results One hundred and twenty patients with severe AS, sixty patients with concentric ventricular remodelling (VR), and hundred controls (CTRL) were prospectively included and underwent non-invasive evaluation of intracardiac flow dynamics. In addition to standard echocardiography, fluid dynamics were assessed by means of HyperDoppler. Vortex depth (P < 0.001), vortex length (P = 0.003), vortex intensity (P < 0.001), and vortex area (P = 0.049) were significantly increased in AS compared with CTRL. In addition, mean energy dissipation was significantly higher in AS compared with CTRL (P < 0.001) and VR (P = 0.002). At receiver operating characteristic analysis, vortex depth showed the best discrimination capacity for AS (P < 0.001). Conclusion Changes in fluid dynamics-based HyperDoppler indices can be reliably assessed in patients with AS. Significant changes in vortex depth and intensity can selectively differentiate AS from both concentric remodelling and healthy CTRLs, suggesting that the assessment of intracardiac flow dynamics may provide complementary information to standard echocardiography to better characterize patients' subsets

GOLFIG Chemo-Immunotherapy in Metastatic Colorectal Cancer Patients. A Critical Review on a Long-Lasting Follow-Up

Background: GOLFIG is a chemo-immunotherapy regimen established in preclinical models that combines gemcitabine + FOLFOX (fluoropyrimidine backbone coupled to oxaliplatin) poly-chemotherapy with low-dose s. c. recombinant interleukin-2 (rIL-2) and granulocyte-macrophage colony stimulating factor (GM-CSF). Promising antitumor effects in metastatic colorectal cancer (mCRC) patients were obtained in previous phase II and III trials. Here we report the results of 15 years of follow-up. Methods: This is a multi-institutional retrospective analysis including 179 mCRC patients receiving GOLFIG regimen between June 2002 and June 2018. Sixty-two of them received the treatment as frontline (enrolled in the GOLFIG-2 phase III trial) and 117 as second/third line (49 enrolled in the GOLFIG-1 phase II trial and 68 as compassionate use). One hundred twelve patients showed a primary left side and 67 a primary right side; K/N-ras mutational status was available in 74 cases, and an activating mutation was detected in 33. Kaplan–Meier and Cox regression analyses were carried out to relate PFS and OS with different parameters. Results: Overall, we recorded a mean PFS and OS of 15.28 (95% CI: 10.36–20.20) and 24.6 (95% CI: 19.07–30.14) months, respectively, with 14 patients surviving free of progression for 10 years. This regimen, in our updated survey of the GOLFIG-2 trial, confirmed superiority over FOLFOX in terms of PFS (hazard ratio (HR) = 0.58, p = 0.006) with a trend to a longer OS (HR = 0.69, P = 0.06) in the first line. Our analysis also confirmed significant antitumor activity in pre-treated patients, reporting a mean PFS and OS of 12.55 (95% CI: 7.19–17.9) and 20.28 (95% CI: 14.4–26.13) months, respectively. Immune-related adverse events (irAEs) were recorded in 24% of the cases and were related to a longer survival (HR = 0.36; P = 0.0001). Finally, patients' outcome was not correlated to sex, sidedness, and MT-K/N-ras. Conclusions: The GOLFIG regimen is a reliable underestimated therapeutic option in pre-treated mCRC patients and offers a strong rationale to design further trials

Stress echocardiography in Italian echocardiographic laboratories: A survey of the Italian society of echocardiography and cardiovascular imaging

Background: The Italian Society of Echography and Cardiovascular Imaging (SIECVI) conducted a national survey to understand the volumes of activity, modalities and stressors used during stress echocardiography (SE) in Italy. Methods: We analyzed echocardiography laboratory activities over a month (November 2022). Data were retrieved through an electronic survey based on a structured questionnaire, uploaded on the SIECVI website. Results: Data were obtained from 228 echocardiographic laboratories, and SE examinations were performed in 179 centers (80.6%): 87 centers (47.5%) were in the northern regions of Italy, 33 centers (18.4%) were in the central regions, and 61 (34.1%) in the southern regions. We annotated a total of 4057 SE. We divided the SE centers into three groups, according to the numbers of SE performed: &lt;10 SE (low-volume activity, 40 centers), between 10 and 39 SE (moderate volume activity, 102 centers) and &gt;= 40 SE (high volume activity, 37 centers). Dipyridamole was used in 139 centers (77.6%); exercise in 120 centers (67.0%); dobutamine in 153 centers (85.4%); pacing in 37 centers (21.1%); and adenosine in 7 centers (4.0%). We found a significant difference between the stressors used and volume of activity of the centers, with a progressive increase in the prevalence of number of stressors from low to high volume activity (P = 0.033). The traditional evaluation of regional wall motion of the left ventricle was performed in all centers, with combined assessment of coronary flow velocity reserve (CFVR) in 90 centers (50.3%): there was a significant difference in the centers with different volume of SE activity: the incidence of analysis of CFVR was significantly higher in high volume centers compared to low - moderate - volume (32.5%, 41.0% and 73.0%, respectively, P &lt; 0.001). The lung ultrasound (LUS) was assessed in 67 centers (37.4%). Furthermore for LUS, we found a significant difference in the centers with different volume of SE activity: significantly higher in high volume centers compared to low - moderate - volume (25.0%, 35.3% and 56.8%, respectively, P &lt; 0.001). Conclusions: This nationwide survey demonstrated that SE was significantly widespread and practiced throughout Italy. In addition to the traditional indication to coronary artery disease based on regional wall motion analysis, other indications are emerging with an increase in the use of LUS and CFVR, especially in high-volume centers