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991.
Jing Xu Ray Siferd Robert L. Ewing 《Analog Integrated Circuits and Signal Processing》1999,20(3):193-201
Unique designs for CMOS analog arithmetic circuits are presented which perform addition (V1 + V2), subtraction (V2 – V1), add/invert –(V1 + V2), and multiply (V1 × V2). The circuit operation is based on the inherent square law of MOS transistor drain current when operating in the saturation region. Key features include: good linearity and accuracy, single ended voltage inputs and output, wide input and output range and no input bias voltages. The circuits can be directly coupled (no buffer) and serve as basic building blocks for analog signal processing implementations such as analog filters and adaptive equalizers. All circuits were implemented in 1.2 m CMOS technology. 相似文献
992.
Eitake Ibaragi Akira Hyogo Keitaro Sekine 《Analog Integrated Circuits and Signal Processing》1999,20(2):119-128
This paper proposes a novel low power dissipation technique for a low voltage OTA. A conventional low power OTA with a class AB input stage is not suitable for a low voltage operation (±1.5 V supply voltages), because it uses composite transistors (referred to CMOS pair) which has a large threshold voltage. On the other hand, the tail-current type OTA needs a large tail-current value to obtain a sufficient input range at the expense of power dissipation. Therefore, the conventional tail-current type OTA has a trade-off between the input range and the power dissipation to the tail-current value. The trade-off can be eliminated by the proposed technique. The technique exploits negative feedback control including a current amplifier and a minimum current selecting circuit. The proposed technique was used on Wang's OTA to create another OTA, named Low Power Wang's OTA. Also, SPICE simulations are used to verify the efficiency of Low Power Wang's OTA. Although the static power of Low Power Wang's OTA is 122 W, it has a sufficient input range, whereas conventional Wang's OTA needs 703 W to obtain a sufficient input range. However, we can say that as the input signal gets larger, the power of Low Power Wang's OTA becomes larger. 相似文献
993.
994.
Robert C. Moore Marian Borkowski Michael G. Bronikowski Jianfeng Chen Oleg S. Pokrovsky Yuanxian Xia Gregory R. Choppin 《Journal of solution chemistry》1999,28(5):521-531
The stability constants of NpO
2
+
, UO
2
2+
Am3+, and Th4+ with acetate and lactate anions has been measured in 0.3–5.0m NaCl media at 25°C by the solvent extraction technique. For the 1:1 complexation, the values of the stability constants increased in the order: NpO
2
+
< Am3+ <
2
2+
< Th4+, in accordance with the actinide charge density and reflecting the strongly ionic bonding of the complexes. The Pitzer ionic interaction parameters were calculated and used to estimate the thermodynamic stability constants at I = 0. Because our data were collected mainly in the high ionic strength region values of (1) were estimated from values reported in the literature. For all stability constants the Pitzer model gives an excellent representation of the data using three interaction parameters (0), (1), and COn leave from Institute of 相似文献
995.
Ab initio calculations at the RHF/6-31G* and MP2/6- 31G*//RHF/6-31G* levels of theory are performed for 2-methyl-4-carboxamido-oxazoles and -thiazoles, including rotational profiles for the ring-carboxamide bond, which showed the expected conjugation and hydrogen bonding effects. On the basis of these data, newly optimised stretch, bend and torsional parameters for the AMBER* force field are derived, along with CHELPG-fitted partial atomic charges. 相似文献
996.
软件复用技术实现策略研究 总被引:1,自引:0,他引:1
首先分析和提出了一种基于OWE(ObjectWith Event)的软构件描述方法,然后深入探讨了如何利用面向对象方法实现软件复用的策略,最后着重分析了继承机制对软件复用的支持以及在分布处理环境中的改进方案. 相似文献
997.
信息隐写与隐写分析研究框架探讨 总被引:3,自引:1,他引:2
文章分析了广义信息隐藏研究中存在的问题,提出引入全信息理论和模糊信息处理的思想进行研究-对信息空间从三个层面上进行了分类,将隐写和隐写分析问题放在信息空间中进行研究,建立了隐写分析研究框架. 相似文献
998.
通过工程调查发现,一些民用房屋改造成移动通信机房过程中由于设备布置不当,对结构构件的安全产生严重的影响,针对一具体问题进行楼板承栽力计算分析并提出相应的处理措施,供设计人员探讨。 相似文献
999.
1000.
We review our recent work in the implementation of optical single-sideband (OSSB) modulation and in the application of this modulation format to microwave photonics and optical testing systems. We have developed an enhanced OSSB modulator for wide-band operation, the so-called bidirectional OSSB modulator, and a simplification of this scheme for narrow-band applications. These OSSB modulators are based on the use of a standard single-electrode Mach-Zehnder electro-optic modulator (MZ-EOM) and passive fiber-optic components. In both designs, the OSSB operation is shown to be independent of the MZ-EOM bias. Therefore, the optical modulation depth at the output of the device can be enhanced using minimum transmission biasing to provide suppression of the optical carrier. Finally, we demonstrate the application of OSSB modulators to the improvement of microwave/millimeter-wave subcarrier multiplexing fiber-optic links and to narrow-band fiber radio systems. In addition, we analyzed the feasibility and the limitations of an optical vector network analysis technique based on OSSB modulation that can provide sub-picometer wavelength resolution. 相似文献