SHicon-based resonant-cavity-enhanced photodetectors

Silicon-based resonant-cavity-enhanced photodetectors (RCE-PD) with Si, Ge islands and InGaAs as absorption materials were introduced, respectively. The Ge islands and Si RCE-PD had a membrane structure and the Si-based InGaAs RCE-PDs were fabricated by bonding technology.

A wide-band front-end for terrestrial and cable receptions

In this paper, a wide-band low noise amplifier, two mixers and a VCO with its buffers implemented in 50GHz 0.35 mu m SiGe BiCMOS technology for dual-conversion digital TV tuner front-end is presented. The LNA and up-converting mixer utilizes current injection technology to achieve high linearity. Without using inductors, the LNA achieves 0.1-1GHz wide bandwidth and 18.8-dB gain with less than 1.4-dB gain variation. The noise figure of the LNA is less than 5dB and its 1dB compression point is -2 dBm. The IIP3 of two mixers is 25-dBm. The measurement results show that the VCO has -127.27-dBc/Hz phase noise at 1-MHz offset and a linear gain of 32.4-MHz/V between 990-MHz and 1.14-GHz. The whole chip consume 253mW power with 5-V supply.

A standard CMOS compatible monolithic photo-detector and trans-impedance amplifier

A 1GHz monolithic photo-detector (PD) and trans-impedance amplifier (TIA) is designed with the standard 0.35 mu m CMOS technique. The design of the photo-detector is analyzed and the CMOS trans-impedance amplifier is also analyzed in the paper. The integrating method is described too. The die photograph is also showed in the paper.

Si-based membrane resonant cavity enhanced photodetectors

Si-based membrane RCE photodetectors were introduced. The RCE photodiodes were fabricated on silicon membranes formed from SOI substrate. Compared with the conventional p-i-n photodiode, the responsivity has a threefold enhancement.

The wideband high-linearity mixers for cable television tuner application

The wideband high-linearity mixers for a double conversion cable TV tuner is presented. The up-conversion mixer converts the input signal from 100MHz to 1000 MHz to the intermediate frequency (IF) of I GHz above. And the down-conversion mixer converts the frequency back. The degeneration resistors are used to Improve the linearity. The tuner is implemented in a 0.35 mu m SiGe technology. Input power at 1dB compression point can reach +14.23dBm. The lowest noise figure is 17.5dB. The two mixers consume 103mW under a supply voltage of 5 V.

A high-gain high-linearity wide-band low noise amplifier for terrestrial and cable receptions

This paper presents the design of a wide-band low-noise amplifier (LNA) implemented in a 0.35 mu m SiGe BiCMOS technology for cable (DVB-C) and terrestrial (DVB-T) tuner applications. The LNA utilizes current injection to achieve high linearity. Without using inductors, the LNA achieves 0.1-1GHz wide bandwidth and 18.8-dB gain with less than 1.4-dB gain variation. The noise figure(NF) of the wideband LNA is 5dB, its 1-dB compression point is -2dBm and IIP3 is 8dBm. The LNA dissipates 120mW power with a 5-V supply.

An ambient proof and wide tuning range LC VCO with automatic amplitude control for tuner applications

This paper represents a LC VCO with AAC (Auto Amplitude Control), in which PMOS FETs are used as active components, and the varactors are directly connected to ground to widen Kvco linear range. The AAC circuitry adds little noise to the VCO and provides it with robust performance over a wide temperature and carrier frequency range. The VCO is fabricated in 50-GHz 0.35-mu m SiGe BiCMOS process. The measurement results show that it has -127.27-dBc/Hz phase noise at 1-MHz offset and a linear gain of 32.4-MHz/V between 990-MHz and 1.14-GHz. The whole circuit draws 6.6-mA current from 5.0-V supply.

Fabrication of low cost Si-based tunable high performance resonant cavity enhanced photodetectors

Low cost Si-based tunable InGaAs RCE photodetectors operating at 1.3similar to1.6 mum were fabricated using sol-gel bonding. A tuning range of 14.5 nm, a quantum efficiency of 44% at 1476 nm and a 3-dB bandwidth of 1.8 GHz were obtained.

Behavior model of a CMOS process compatible photo-diode

A behavior model of a photo-diode is presented. The model describes the relationship between photocurrent and incident optical power, and it also illustrates the impact of the reverse bias to the variation of the junction capacitance. With this model, the photo-diode and a CMOS receiver circuit were simulated and designed simultaneously under a universal circuit simulation environment.

1.55 mu m Ge islands resonant-cavity-enhanced narrowband detector

The high quality Ge islands material with 1.55 mu m photo-response grown on Sol substrate is reported. Due to the modulation of the cavity formed by the mirrors at the surface and the buried SiO2 interface, seven sharp and strong peaks with narrow linewidth are found. And a 1.55 mu m Ge islands resonant-cavity-enhanced (RCE) detector with narrowband was fabricated by a simple method. The bottom mirror was deposited in the hole formed by anisotropically etching, in a basic solution from the backside of the sample with the buried SiO2 layer in silicon-on-insulator substrate as the etch-stop layer. Reflectivity spectrum indicates that the mirror deposited in the hole has a reflectivity as high as 99% in the range of 1.2-1.65 mu m. The peak responsivity of the RCE detector at 1543.8 nm is 0.028 mA/W and a full width at half maximum of 5 nm is obtained. Compared with the conventional p-i-n photodetector, the responsivity of RCE detector has a nearly threefold enhancement.

一种基于身份的多信任域网格认证模型

分析了现有的网格认证框架中存在的问题，提出了一种基于身份的多信任域网格认证模型．该模型以基于身份的PKI为基础，避免了基于传统PKI的认证框架的诸多缺点．同时，该模型提供了跨信任域的双向实体认证功能．模拟试验表明，该认证模型比基于传统PKI的认证框架更轻量、更高效．而且由于该模型可以在多信任域的环境下工作，故而比W Mao提出的只能在单一信任域中工作的认证框架更符合网格认证的实际需要．

Micromixing enhanced by pulsating flows

We consider the micromixing enhancement by pulsating flows. Dimensionless governing equations and boundary conditions were developed for T-type micromixers with two inlet pulsating flows. The problem involves a set of parameters. Three key dimensionless parameters are identified: the Reynolds number, the Strouhal number, and the disturbance amplitude. Suitable Strouhal number or disturbance amplitude causes symmetrical meniscus-shape mixing interfaces, separating the whole mixing channel into a set of segments. Thus uniform exit species concentration can be reached. Too large or too small Strouhal number or disturbance amplitude yields the meniscus-shape mixing interfaces deviating from the centerline of the mixing channel, deteriorating the mixing performance. The optimized disturbance amplitude is increased with increases in Strouhal numbers. Low Reynolds number needs larger disturbance amplitude.

茂稀土及其单组分催化剂催化聚合的研究

本论文分为两个部分：第一部分从考察茂基稀土化合物中的配体结构对其催化烯烃聚合行为的影响规律出发，合成了几种单茂基稀土化合物，双茂基稀土化合物和桥联双茂基稀土化合物等氯化物和桥联双茂基稀土胺化物，并对其进行了表征。第二部分考察了茂基稀土化合物对烯烃和极性单体的聚合行为，尤其重点考察了桥联茂基稀土胺化物对极性单体甲基丙烯酸甲酯的聚合行为，并对聚合产物进行了表征。主要结果如下：一．茂基稀土化合物的合成与表征：1．单茂基稀土化合物的合成与表征：合成了五种环戊二烯基及其不同立体位阻的取代化合物的单茂基稀土化合物，并对其进行了元素分析，对部分化合物进行了红外光谱分析。其中，有两种化合物的合成尚未见报道。2．双茂基稀土化合物的合成与表征合成了五种双茂基稀土化合物，并对其进行了元素分析，部分化合物进行了红外光谱分析。其中有两种化合物的合成尚未见报道。3．桥联双茂基稀土化合物的合成与表征：合成了八种桥联双茂基稀土化合物，对其进行了元素分析，并对其中部分化合物进行了红外光谱和~1H核磁共振分析。4．桥联双茂基稀土胺化物的合成：从稳定催化剂活性中心，设计更理想的活性配位聚合催化剂的目的出发，首次合成了三种桥联双茂基稀土胺化物。二．茂基稀土化合物催化烯烃和极性单体聚合1．以单茂基稀土化合物/MAO体系为催化剂，考察了其对丁二烯、异戊二烯和苯乙烯的聚合行为，并从合成性能优异的橡胶材料-丁二烯/异戊二烯/苯乙烯三元共聚物出发，初步考察了三种单体的共聚合行为。2．以桥联双茂基稀土胺化物为催化剂，重点考察了其对极性单体甲基丙烯酸甲酯的聚合行为，包括催化剂浓度、单体浓度、单体/催化剂比例和聚合温度等因素对聚合物的分子量、分子量分布、转化率和聚合物的立体规整性的影响。认为桥联茂基稀土胺化物单独即可有效地催化甲基丙烯酸甲酯的聚合，聚合有活性特征，聚合物的分子量随催化剂浓度的减少而增大，分子量分布随聚合温度的降低而变窄。桥联茂基稀土胺化物在相同的聚合条件下，催化甲基丙烯酸甲酯聚合的聚合产物与非桥联茂基稀土胺化物的相比较，具有更低的分子量，更窄的分子量分布，更高的立体规整性，说明桥联茂基稀土胺化物可以使催化剂的活性中心更稳定，使其具有更优异的聚合性能。

含β-二酮结构高性能聚合物的合成、表征与性能

合成出12种β-二酮化合物：1-（4-硝基苯基)-3-苯基-1,3-丙二酮(1)、1-(3-硝基苯基)-3-苯基-1,3-丙二酮(2)、1-(4-胺基苯基)-3-苯基-1,3-丙二酮(3)、1-(3-胺基苯基)-3-苯基-1,3-丙二酮(4)、1-(4-马来酰亚胺基苯基)-3-苯基-1,3-丙二酮(5)、1-(3-马来酰亚胺基苯基)-3-苯基-1,3-丙二酮(6)、1,3-双(3一硝基苯基)-1，3-丙二酮(7)、1-(3-硝基苯基)-3-(4-硝基苯基)-1,3-丙二酮(8)、1,3-双(4-硝基苯基)-1,3-丙二酮(9)；1,3-双(3-氨基苯基)-1,3-丙二酮(10)、1-(3-氨基苯基)-3-(4-氨基苯基)-1,3-丙二酮(11)、1,3-双(4-氨基苯基)-1,3-丙二酮(12)。12种化合物的结构均经多种光谱表征方法得到证实。采用定量~1H和~(13)C-NMR方法测定了化合物5-12酮式、烯醇式异构体的含量；烯醇式-酮式互变异构平衡常数；以及化合物5、6、8、lO烯醇式异构体的相对百分比。应用荧光光谱法研究了化合物的荧光性能，比较了取代基位置对其荧光性能的影响。以化合物5和6为单体，成功地制备出侧链含有B-二酮结构的2种马来酰亚胺均聚物。聚合研究结果表明间位取代的单体聚合速率明显大于对位取代的单体。光谱表征结果表明均聚物侧链的B-二酮基团主要以其烯醇式的形式存在，但是由于琥珀酰亚胺的共轭效应小于马来酰亚胺的共轭效应，因此均聚物的酮式异构体含量较之单体相对增大。荧光光谱研究表明虽然均聚物酮式异构体含量较高，但受大分子结构的影响，其荧光强度较小分子类似物有所降低。均聚物性能测试结果表明间位取代的均聚物较之对位取代的均聚物表现出较高的热性能。以甲基丙烯酸甲酯(MMA)、苯乙烯(St)、乙烯基正丁醚(BVE)、甲基丙烯酸正丁酯(BMA)、4-乙烯基吡啶(VPy)、1-乙烯基咪唑(VI)为第二单体，分别同化合物5和6共聚合成功地制备出十一种马来酰亚胺共聚物。共聚合研究结果表明，依第二单体的不同，部分共聚物表现出典型的交替共聚物性质，如第二单体为St、PPy和VI。当第二单体含有强质子受体性能的基团，如吡啶基和咪唑基时，同β-二酮基团的烯醇式存在大分子链内的分子间氢键作用。这种分子内氢键的相互作用，直接导致共聚物荧光性能的增强。此外，所有共聚物在保持良好的热稳定性能基础上，平均分子量均有相当大的提高，共聚物数均分子量最高者可达十几万。与此同时，共聚物的溶解性能也得到了彻底的改善，所有共聚物均可溶于氯仿、丙酮、四氢呋喃等溶剂。根据共聚微分方程，采用斜率截距法分别测定了十一组共聚体系的竞聚率。进而应用Alfrey-Price方程，求得的单体5和6的Q值和e值。单体5的平均Q和e值分别为1.08和1.94；单体6的平均Q和e值分别为1.05和1.69。以二胺单体10、11和12同多种二酐经由聚酰胺酸热或化学环化首次成功地合成出二十几种主链含有β-二酮结构的聚酰亚胺。粘度实验表明，由3种二胺合成的聚酰胺酸分子量都不高在0.30-1.09dL/g之间变化。比较3种二胺单体与相同二酐制备的聚酰胺酸分子量，其的大小次序为：10 > 11 > 12。溶解性实验表明由含有柔性桥联基团，如O，C(CF_3)_2，SO_2和C(CH_3)_2基团的二酐制备的聚酰亚胺表现出良好的溶解性，其中，同一种二酐与3种二胺单体制备的聚酰亚胺的溶解性的大小次序为：10 > 11 > 12。所得聚酰亚胺均表现出较高的玻璃化转变温度，如200℃以上，和热分解温度，如10％热失重温度于氮气和空气氛下均在400℃以上。广角X射线衍射分析表明多数聚酰亚胺为非晶聚合物，但是依二胺和二酐结构的不同，部分聚酰亚胺形态结构呈现出一定的有序性。比较含3种二胺单体的聚酰亚胺膜性能，以含二胺单体10的聚酰亚胺膜性能最佳。拉伸实验结果给出其断裂伸长率在2-6%之间；抗张强度在29-72Mpa之间；杨氏模量在1414-2111Mpa之间。二胺的活性取决于氨基的电子给予性，而氨基的电子给予性与氨基质子和直接联于氨基的碳原子化学位移密切相关。因此，由其化学位移的大小可推断出二胺的活性。根据NMR测得的二胺的氨基质子或直接联于氨基的碳原子化学位移，二胺活性的大小次序为：10 > 11 > 12。二胺结构对聚酰亚胺性能的影响主要来自二胺分子的空间立体结构或分子结构的对称性。二胺的线性越差，聚酰亚胺的溶解性越好；而二胺分子的对称性越好、刚性越强，聚酰亚胺的Tg越高。因此，比较三种二胺的结构，不难得出含3种二胺单体的聚酰亚胺的溶解性大小次序为：10 > 11 > 12，而含3种二胺单体的聚酰亚胺的Tg大小次序为：12 > 11 > 10。以上推论与实验结果完全一致。在成功地合成出主、侧链含β-二酮结构高性能聚合物的基础上，我们对β-二酮聚合物的光化学和配位化学性质进行了初步探索性研究。β-二酮聚合物的光化学性质研究表明，由于大分子结构的影响聚合物光酮化过程的暗反应变得非常之缓慢，因此，光酮化过程很难趋于平衡。聚合物与二乙烯基苯的光加成交联反应研究结果表明，在紫外光照条件下，聚合物与二乙烯基苯发生了光加成交联反应。以β-二酮聚合物作为配体兼载体同四氯化钛配合反应，成功地制备出聚合物负载过渡金属钛配合物催化剂。配合物催化剂的结构分析表明钛与聚合物配体存在多种配位形式。所得催化剂同MAO组成的催化体系可有效催化乙烯的配位聚合反应，在铝钛比仅为200时，催化剂的聚合活性可达3.9 * 10~5g/molTi·h。由于多种配位形式导致的多催化活性中心，因此，所得聚乙烯具有较宽的结晶熔融温度范围。该催化体系同样可有效催化苯乙烯的间同聚合。本体聚合铝钛比为200时，其聚合活性为5.2 * 104g/molTi·h。所得聚苯乙烯熔点温度达263 ℃，为典型的间同聚苯乙烯。以化合物5或6为配体，合成出三种三元稀土离子铕配合物单体。以上述三种配合物单体同MMA或St共聚制备出三种稀土聚合物配合物。考察了聚合物配合物荧光强度与其结构和铕含量的关系。所得聚合物配合物均为白色粉末，易溶于常用有机溶剂如氯仿、丙酮和四氢呋喃等。采用溶液浇铸法或旋转涂膜法，可方便地制备成无色透明薄膜。在紫外光激发下，薄膜发出特征的红色稀土离子铕的荧光。遗憾的是，在我们试图将聚合物配合物用于电致发光研究中，没有获得成功。