This paper presents the design and testing of a 15 Gbps non-return-to-zero(NRZ),30 Gbps 4-level pulse amplitude modulation(PAM4)configurable laser diode driver(LDD)implemented in 0.15-μm GaAs E-mode pHEMT technology....This paper presents the design and testing of a 15 Gbps non-return-to-zero(NRZ),30 Gbps 4-level pulse amplitude modulation(PAM4)configurable laser diode driver(LDD)implemented in 0.15-μm GaAs E-mode pHEMT technology.The driver bandwidth is enhanced by utilizing cross-coupled neutralization capacitors across the output stage.The output transmission-line back-termination,which absorbs signal reflections from the imperfectly matched load,is performed passively with on-chip 50-Ωresistors.The proposed 30 Gbps PAM4 LDD is implemented by combining two 15 Gbps-NRZ LDDs,as the high and low amplification paths,to generate PAM4 output current signal with levels of 0,40,80,and 120 mA when driving 25-Ωlasers.The high and low amplification paths can be used separately or simultaneously as a 15 Gbps-NRZ LDD.The measurement results show clear output eye diagrams at speeds of up to 15 and 30 Gbps for the NRZ and PAM4 drivers,respectively.At a maximum output current of 120 mA,the driver consumes 1.228 W from a single supply voltage of-5.2 V.The proposed driver shows a high current driving capability with a better output power to power dissipation ratio,which makes it suitable for driving high current distributed feedback(DFB)lasers.The chip occupies a total area of 0.7×1.3 mm^(2).展开更多
The self-reinforced Si<sub>3</sub>N<sub>4</sub> ceramics which contain Y<sub>2</sub>O<sub>3</sub> and La<sub>2</sub>O<sub>3</sub> additives have ...The self-reinforced Si<sub>3</sub>N<sub>4</sub> ceramics which contain Y<sub>2</sub>O<sub>3</sub> and La<sub>2</sub>O<sub>3</sub> additives have beenprepared by hot-pressing. Under the optimum processing conditions, this material has theflexural strength of 960～1050MPa and the fracture toughness of 11.17～12.74MPa·m<sup>1/2</sup> atroom-temperature, and 720～780MPa and 22～24MPa·m<sup>1/2</sup> at 1350℃. The effects of heating rate, sintering temperature, and holding time on the microstructures and mechanical properties are investigated. The experimental results show that an appropriate β-Si<sub>3</sub>N<sub>4</sub> grainsize and homogeneous microstructure can be obtained under the conditions of a heating rate of 10℃/min, sintering temperature of 1800℃, and holding time of 1h, which are advantageous to enhancing the mechanical properties. Crack deflection in large rodlike β-Si<sub>3</sub>N<sub>4</sub> grains is a principle source of toughening.展开更多
The mobile multicast technology has been a research hotspot in the wireless Internet field in recent years.Quite a large part of its applications requires the reliability in a mobile environment to be equivalent to th...The mobile multicast technology has been a research hotspot in the wireless Internet field in recent years.Quite a large part of its applications requires the reliability in a mobile environment to be equivalent to that provided by wireline links.However,the inherent features of a mobile environment,that is,high error rate of links and dynamically changing multicast members’ locations,are great difficulties for mobile multicast,let alone reliable mobile multicast.The IPv4-based reliable mobile multicast algorithms come with two different design philosophies.A part of the algorithms is to be improved for better reliability by solving existing algorithm-related problems;while other algorithms are to implement reliable mobile multicast with new function entities introduced to guarantee reliability.展开更多
In this paper, we have investigated the design parameters of RF CMOS switch, which will be used for the wireless tele-communication systems. A double-pole four-throw double-gate radio-frequency complementary-metal-oxi...In this paper, we have investigated the design parameters of RF CMOS switch, which will be used for the wireless tele-communication systems. A double-pole four-throw double-gate radio-frequency complementary-metal-oxide-semicon- ductor (DP4T DG RF CMOS) switch for operating at the 1 GHz is implemented with 45-nm CMOS process technology. This proposed RF switch is capable to select the data streams from the two antennas for both the transmitting and receiving processes. For the development of this DP4T DG RF CMOS switch we have explored the basic concept of the proposed switch circuit elements required for the radio frequency systems such as drain current, threshold voltage, resonant frequency, return loss, transmission loss, VSWR, resistances, capacitances, and switching speed.展开更多
目的分析乳腺影像报告及数据系统(breast imaging reporting and data system,BI-RADS)4类乳腺良恶性结节采用超声弹性成像(ultrasonic elastography,UE)技术诊断的价值。方法选择2023年1—11月济南市章丘区人民医院收治的102例疑似BI-R...目的分析乳腺影像报告及数据系统(breast imaging reporting and data system,BI-RADS)4类乳腺良恶性结节采用超声弹性成像(ultrasonic elastography,UE)技术诊断的价值。方法选择2023年1—11月济南市章丘区人民医院收治的102例疑似BI-RADS 4类乳腺实性结节患者为研究对象,全部患者均接受彩色多普勒超声与UE检查。以病理结果为“金标准”,针对BI-RADS 4类乳腺良恶性结节经常规超声与UE技术诊断的结果及效能,以及对UE技术诊断结果与病理结果的一致性进行评价。结果BI-RADS 4类乳腺良恶性结节经穿刺活检结果证实为恶性36例,良性66例,UE技术诊断结果与病理诊断结果具有极好的一致性(kappa=0.890)。UE技术对BI-RADS 4类乳腺良恶性结节诊断的灵敏度94.44%、特异度95.45%、准确度95.10%均高于常规超声的72.22%、81.82%、78.43%,差异有统计学意义(χ^(2)=6.400、6.092、12.337,P均<0.05)。结论UE在BI-RADS 4类乳腺良恶性结节中具有较为理想的诊断价值,进一步提高了诊断效能,为临床提供可靠的参考信息。展开更多
The Chinese Society of Astro-nautics (CSA) and International Academy of Astronautics (IAA) jointly held the 4th CSA-IAA Conference on Advanced Space Technology from September 5 to 8, 2011 in
文摘This paper presents the design and testing of a 15 Gbps non-return-to-zero(NRZ),30 Gbps 4-level pulse amplitude modulation(PAM4)configurable laser diode driver(LDD)implemented in 0.15-μm GaAs E-mode pHEMT technology.The driver bandwidth is enhanced by utilizing cross-coupled neutralization capacitors across the output stage.The output transmission-line back-termination,which absorbs signal reflections from the imperfectly matched load,is performed passively with on-chip 50-Ωresistors.The proposed 30 Gbps PAM4 LDD is implemented by combining two 15 Gbps-NRZ LDDs,as the high and low amplification paths,to generate PAM4 output current signal with levels of 0,40,80,and 120 mA when driving 25-Ωlasers.The high and low amplification paths can be used separately or simultaneously as a 15 Gbps-NRZ LDD.The measurement results show clear output eye diagrams at speeds of up to 15 and 30 Gbps for the NRZ and PAM4 drivers,respectively.At a maximum output current of 120 mA,the driver consumes 1.228 W from a single supply voltage of-5.2 V.The proposed driver shows a high current driving capability with a better output power to power dissipation ratio,which makes it suitable for driving high current distributed feedback(DFB)lasers.The chip occupies a total area of 0.7×1.3 mm^(2).
基金Supported by China Postdoctoral Science Foundation
文摘The self-reinforced Si<sub>3</sub>N<sub>4</sub> ceramics which contain Y<sub>2</sub>O<sub>3</sub> and La<sub>2</sub>O<sub>3</sub> additives have beenprepared by hot-pressing. Under the optimum processing conditions, this material has theflexural strength of 960～1050MPa and the fracture toughness of 11.17～12.74MPa·m<sup>1/2</sup> atroom-temperature, and 720～780MPa and 22～24MPa·m<sup>1/2</sup> at 1350℃. The effects of heating rate, sintering temperature, and holding time on the microstructures and mechanical properties are investigated. The experimental results show that an appropriate β-Si<sub>3</sub>N<sub>4</sub> grainsize and homogeneous microstructure can be obtained under the conditions of a heating rate of 10℃/min, sintering temperature of 1800℃, and holding time of 1h, which are advantageous to enhancing the mechanical properties. Crack deflection in large rodlike β-Si<sub>3</sub>N<sub>4</sub> grains is a principle source of toughening.
基金supported by the National High Technology Research and Development Program ("863" Program) under Grant No.2007AA10Z235
文摘The mobile multicast technology has been a research hotspot in the wireless Internet field in recent years.Quite a large part of its applications requires the reliability in a mobile environment to be equivalent to that provided by wireline links.However,the inherent features of a mobile environment,that is,high error rate of links and dynamically changing multicast members’ locations,are great difficulties for mobile multicast,let alone reliable mobile multicast.The IPv4-based reliable mobile multicast algorithms come with two different design philosophies.A part of the algorithms is to be improved for better reliability by solving existing algorithm-related problems;while other algorithms are to implement reliable mobile multicast with new function entities introduced to guarantee reliability.
文摘In this paper, we have investigated the design parameters of RF CMOS switch, which will be used for the wireless tele-communication systems. A double-pole four-throw double-gate radio-frequency complementary-metal-oxide-semicon- ductor (DP4T DG RF CMOS) switch for operating at the 1 GHz is implemented with 45-nm CMOS process technology. This proposed RF switch is capable to select the data streams from the two antennas for both the transmitting and receiving processes. For the development of this DP4T DG RF CMOS switch we have explored the basic concept of the proposed switch circuit elements required for the radio frequency systems such as drain current, threshold voltage, resonant frequency, return loss, transmission loss, VSWR, resistances, capacitances, and switching speed.
文摘The Chinese Society of Astro-nautics (CSA) and International Academy of Astronautics (IAA) jointly held the 4th CSA-IAA Conference on Advanced Space Technology from September 5 to 8, 2011 in
