To build an accurate electric model for through-silicon vias （TSVs） in 3D integrated circuits （ICs）, a resistance and capacitance （RC） circuit model and related efficient extraction technique are proposed. The c...To build an accurate electric model for through-silicon vias （TSVs） in 3D integrated circuits （ICs）, a resistance and capacitance （RC） circuit model and related efficient extraction technique are proposed. The circuit model takes both semiconductor and electrostatic effects into account, and is valid for low and medium signal frequencies. The electrostatic capacitances are extracted with a floating random walk based algorithm, and are then combined with the voltage-dependent semiconductor capacitances to form the equivalent circuit. Compared with the method used in Synopsys＇s Sdevice, which completely simulates the electro/semiconductor effects, the proposed method is more efficient and is able to handle the general TSV layout as well. For several TSV structures, the experimental results validate the accuracy of the proposed method for the frequency range from l0 kHz to 1 GHz. The proposed method demonstrated 47× speedup over the Sdevice for the largest 9-TSV case.展开更多
In this paper, a new type of through-silicon via（TSV） for via-first process namely bare TSV, is proposed and analyzed with the aim of mitigating noise coupling problems in 3D integrated systems for advanced technolo...In this paper, a new type of through-silicon via（TSV） for via-first process namely bare TSV, is proposed and analyzed with the aim of mitigating noise coupling problems in 3D integrated systems for advanced technology nodes. The bare TSVs have no insulation layers, and are divided into two types： bare signal TSVs and bare ground TSVs. First, by solving Poisson＇s equation for cylindrical P–N junctions, the bare signal TSVs are shown to be equivalent to conventional signal TSVs according to the simulation results. Then the bare ground TSV is proved to have improved noise-absorption capability when compared with a conventional ground TSV. Also, the proposed bare TSVs offer more advantages to circuits than other noise isolation methods, because the original circuit design,routing and placement can be retained after the application of the bare TSVs.展开更多
Background: Since 2021, high-risk Human Papilloma Virus (HR-HPV) testing has been the recommended screening test for cervical cancer for all settings;either used alone in a “test and treat” strategy, or with a triag...Background: Since 2021, high-risk Human Papilloma Virus (HR-HPV) testing has been the recommended screening test for cervical cancer for all settings;either used alone in a “test and treat” strategy, or with a triage test, with or without biopsy, before treatment. Cameroon has rolled out immunization against HPV 16 and 18, but studies show a higher prevalence of non-16/18 HR-HPV types. Objectives: Determine the prevalence of precancerous lesions, in women with HR-HPV infection and evaluate association of digital cervicography (DC) VIA/VILI positivity with HPV serotype, as a measure of their contribution to precancer and cancer incidence. Methodology: The study was cross-sectional, descriptive, and analytic. It took place at the Etoug-Ebe and Ekoudoum Baptist Hospitals in Yaoundé, during the period April-September 2022. We reviewed the records of women screened for cervical cancer between February 2020 and December 2021 and evaluated the prevalence of lesions on digital cervicography (DC) with VIA/VILI for women positive for HR-HPV serotypes. The data were analyzed using SPSS version 20.0 for Windows. P values Results: We identified 315 cases with a positive HR-HPV deoxyribonucleic acid (DNA) test, 224 (71.1%) had a DC VIA/VILI triage test done. Of these, 30 (13.4%) women had a positive DC VIA/VILI, with five women (2.2%) having lesions suggestive of cancer. Out of 11 cases positive for HPV 16 alone, 05 (45.5%) had a positive DC VIA/VILI test. Of the 14 cases positive for HPV 18 alone, 03 (21.4%) had a positive VIA/VILI, meanwhile only 19 (10.7%) of the 177 cases positive for non-16/18 HPV had a positive VIA/VILI test. Conclusion: A high proportion of women (13.4%) with HR HPV had a positive DC VIA/VILI, with a significant proportion (2.2%) having lesions suggestive of invasive cervical cancer HR-HPV serotype was associated with DC VIA/VILI positivity;HPV 16 had the strongest association (45.5%), followed by HPV 18 (21.4%), and non-16/18 HR-HPV (10.7%), suggesting a decreasing order of oncogenicity.展开更多
Through-silicon-via （TSV） to TSV crosstalk noise is one of the key factors affecting the signal integrity of three- dimensional integrated circuits （3D ICs）. Based on the frequency dependent equivalent electrical ...Through-silicon-via （TSV） to TSV crosstalk noise is one of the key factors affecting the signal integrity of three- dimensional integrated circuits （3D ICs）. Based on the frequency dependent equivalent electrical parameters for the TSV channel, an analytical crosstalk noise model is established to capture the TSV induced crosstalk noise. The impact of various design parameters including insulation dielectric, via pitch, via height, silicon conductivity, and terminal impedance on the crosstalk noise is analyzed with the proposed model. Two approaches are proposed to alleviate the TSV noise, namely, driver sizing and via shielding, and the SPICE results show 241 rnV and 379 mV reductions in the peak noise voltage, respectively.展开更多
A thermal via has been used to enhance the heat transfer through the printed circuit board (PCB). Because the thermal conductivity of a dielectric material is very low, the array of metal vias is placed to make therma...A thermal via has been used to enhance the heat transfer through the printed circuit board (PCB). Because the thermal conductivity of a dielectric material is very low, the array of metal vias is placed to make thermal paths in the PCB. This paper describes the numerical analysis of the PCB having metal vias and focuses on the heat transfer characteristics under the nonisothermal boundary conditions. The mathematical model of the PCB has the metal vias between two metal sheets. Under 2nd and 3rd kinds of boundary conditions, the temperature distribution is obtained numerically by changing the design parameters. The discussion is also made on the effective thermal conductivity of the PCB. In industry, the use of effective thermal conductivity is convenient for thermal engineers because it simplifies the calculation process, that is, the composite board can be modeled as a homogeneous medium. From the numerical results, it is confirmed that the placement of metal sheets and the population of metal vias are important factors to dominate the heat transfer characteristics of the PCB. It is also shown that although the nonisothermal boundary conditions are applied at the boundary surface, the temperature difference between the heated and the cooled section is almost uniform when the metal vias are populated densely with the metal sheets. In this case, the effective thermal conductivity of the PCB is found to be the same irrespective of the boundary conditions, that is, whether the isothermal or the nonisothermal boundary conditions are applied.展开更多
By placing a sample between a heated and a cooled rod, a thermal conductivity of the sample can be evaluated easily with the assumption of a one-dimensional heat flow. However, a three-dimensional constriction/spreadi...By placing a sample between a heated and a cooled rod, a thermal conductivity of the sample can be evaluated easily with the assumption of a one-dimensional heat flow. However, a three-dimensional constriction/spreading heat flow may occur inside the rods when the sample is a composite having different thermal conductivities. In order to investigate the thermal resistance due to the constriction/spreading heat flow, the three-dimensional numerical analyses were conducted on the heat transfer characteristics of the rods. In the present analyses, a polymer-based composite board having thermal vias was sandwiched between the rods. From the numerical results, it was confirmed that the constriction/spreading resistance of the rods was strongly affected by the thermal conductivity of the rods as well as the number and size of the thermal vias. A simple equation was also proposed to evaluate the constriction/spreading resistance of the rods. Fairly good agreements were obtained between the numerical results and the calculated ones by the simple equation. Moreover, the discussion was also made on an effective thermal conductivity of the composite board evaluated with the heated and the cooled rod.展开更多
基金supported by the National Natural Science Foundation of China(No.61422402)the Tsinghua University Initiative Scientific Research Program
文摘To build an accurate electric model for through-silicon vias （TSVs） in 3D integrated circuits （ICs）, a resistance and capacitance （RC） circuit model and related efficient extraction technique are proposed. The circuit model takes both semiconductor and electrostatic effects into account, and is valid for low and medium signal frequencies. The electrostatic capacitances are extracted with a floating random walk based algorithm, and are then combined with the voltage-dependent semiconductor capacitances to form the equivalent circuit. Compared with the method used in Synopsys＇s Sdevice, which completely simulates the electro/semiconductor effects, the proposed method is more efficient and is able to handle the general TSV layout as well. For several TSV structures, the experimental results validate the accuracy of the proposed method for the frequency range from l0 kHz to 1 GHz. The proposed method demonstrated 47× speedup over the Sdevice for the largest 9-TSV case.
基金Project supported by the National Basic Research Program of China (No. 2015CB0572)the Importation and Development of HighCaliber Talents Project of Beijing Municipal Institutions (No. CIT&TCD20150320)the National Natural Science Foundation of China (No. 61176102)
文摘In this paper, a new type of through-silicon via（TSV） for via-first process namely bare TSV, is proposed and analyzed with the aim of mitigating noise coupling problems in 3D integrated systems for advanced technology nodes. The bare TSVs have no insulation layers, and are divided into two types： bare signal TSVs and bare ground TSVs. First, by solving Poisson＇s equation for cylindrical P–N junctions, the bare signal TSVs are shown to be equivalent to conventional signal TSVs according to the simulation results. Then the bare ground TSV is proved to have improved noise-absorption capability when compared with a conventional ground TSV. Also, the proposed bare TSVs offer more advantages to circuits than other noise isolation methods, because the original circuit design,routing and placement can be retained after the application of the bare TSVs.
文摘Background: Since 2021, high-risk Human Papilloma Virus (HR-HPV) testing has been the recommended screening test for cervical cancer for all settings;either used alone in a “test and treat” strategy, or with a triage test, with or without biopsy, before treatment. Cameroon has rolled out immunization against HPV 16 and 18, but studies show a higher prevalence of non-16/18 HR-HPV types. Objectives: Determine the prevalence of precancerous lesions, in women with HR-HPV infection and evaluate association of digital cervicography (DC) VIA/VILI positivity with HPV serotype, as a measure of their contribution to precancer and cancer incidence. Methodology: The study was cross-sectional, descriptive, and analytic. It took place at the Etoug-Ebe and Ekoudoum Baptist Hospitals in Yaoundé, during the period April-September 2022. We reviewed the records of women screened for cervical cancer between February 2020 and December 2021 and evaluated the prevalence of lesions on digital cervicography (DC) with VIA/VILI for women positive for HR-HPV serotypes. The data were analyzed using SPSS version 20.0 for Windows. P values Results: We identified 315 cases with a positive HR-HPV deoxyribonucleic acid (DNA) test, 224 (71.1%) had a DC VIA/VILI triage test done. Of these, 30 (13.4%) women had a positive DC VIA/VILI, with five women (2.2%) having lesions suggestive of cancer. Out of 11 cases positive for HPV 16 alone, 05 (45.5%) had a positive DC VIA/VILI test. Of the 14 cases positive for HPV 18 alone, 03 (21.4%) had a positive VIA/VILI, meanwhile only 19 (10.7%) of the 177 cases positive for non-16/18 HPV had a positive VIA/VILI test. Conclusion: A high proportion of women (13.4%) with HR HPV had a positive DC VIA/VILI, with a significant proportion (2.2%) having lesions suggestive of invasive cervical cancer HR-HPV serotype was associated with DC VIA/VILI positivity;HPV 16 had the strongest association (45.5%), followed by HPV 18 (21.4%), and non-16/18 HR-HPV (10.7%), suggesting a decreasing order of oncogenicity.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61131001,61322405,61204044,61376039,and 61334003)
文摘Through-silicon-via （TSV） to TSV crosstalk noise is one of the key factors affecting the signal integrity of three- dimensional integrated circuits （3D ICs）. Based on the frequency dependent equivalent electrical parameters for the TSV channel, an analytical crosstalk noise model is established to capture the TSV induced crosstalk noise. The impact of various design parameters including insulation dielectric, via pitch, via height, silicon conductivity, and terminal impedance on the crosstalk noise is analyzed with the proposed model. Two approaches are proposed to alleviate the TSV noise, namely, driver sizing and via shielding, and the SPICE results show 241 rnV and 379 mV reductions in the peak noise voltage, respectively.
文摘A thermal via has been used to enhance the heat transfer through the printed circuit board (PCB). Because the thermal conductivity of a dielectric material is very low, the array of metal vias is placed to make thermal paths in the PCB. This paper describes the numerical analysis of the PCB having metal vias and focuses on the heat transfer characteristics under the nonisothermal boundary conditions. The mathematical model of the PCB has the metal vias between two metal sheets. Under 2nd and 3rd kinds of boundary conditions, the temperature distribution is obtained numerically by changing the design parameters. The discussion is also made on the effective thermal conductivity of the PCB. In industry, the use of effective thermal conductivity is convenient for thermal engineers because it simplifies the calculation process, that is, the composite board can be modeled as a homogeneous medium. From the numerical results, it is confirmed that the placement of metal sheets and the population of metal vias are important factors to dominate the heat transfer characteristics of the PCB. It is also shown that although the nonisothermal boundary conditions are applied at the boundary surface, the temperature difference between the heated and the cooled section is almost uniform when the metal vias are populated densely with the metal sheets. In this case, the effective thermal conductivity of the PCB is found to be the same irrespective of the boundary conditions, that is, whether the isothermal or the nonisothermal boundary conditions are applied.
文摘By placing a sample between a heated and a cooled rod, a thermal conductivity of the sample can be evaluated easily with the assumption of a one-dimensional heat flow. However, a three-dimensional constriction/spreading heat flow may occur inside the rods when the sample is a composite having different thermal conductivities. In order to investigate the thermal resistance due to the constriction/spreading heat flow, the three-dimensional numerical analyses were conducted on the heat transfer characteristics of the rods. In the present analyses, a polymer-based composite board having thermal vias was sandwiched between the rods. From the numerical results, it was confirmed that the constriction/spreading resistance of the rods was strongly affected by the thermal conductivity of the rods as well as the number and size of the thermal vias. A simple equation was also proposed to evaluate the constriction/spreading resistance of the rods. Fairly good agreements were obtained between the numerical results and the calculated ones by the simple equation. Moreover, the discussion was also made on an effective thermal conductivity of the composite board evaluated with the heated and the cooled rod.
