一种CMOS高速采样/保持放大器

文章分析了采样／保持电路的基本原理，设计了一种CMOS高速采样／保持放大器，采样频率可达到50MHz，并用TSMC的0．35μm标准CMOS工艺库模拟了整体电路和分块电路的性能。     

框架去噪在A/D转换中的应用

在信号传输的过程中，原始模拟信号首先要转换成数字信号（A/D），这就要对信号进行采样，量化，为了信号接受不失真，从硬件实现来看增加采样速率比增加量化精度更容易实现，在采样速率大于采样定理所要求的速率时，信号值之间的冗余度也增加了，从整体来看，对信号的量化误差接近于白噪声，而框架去噪就利用框架对过采样的信号进行变换重构，从而达到去噪的目的。     

高分辨率流水线A/D转换器采样电容优化研究

讨论了流水线A／D转换器的工作原理，定量分析了开关电容增益块中最重要的两个热噪声源：采样开关和放大器的热噪声。以此为基础，提出了使功耗最小化的采样电容选择方法，以及在简单模型下的取值。在对A／D转换器进行功耗优化时，分析结果对选择采样电容和每级分辨率具有指导意义。     

二重结构30 MSPS采样/保持电路的研究与探讨

通过理论分析和实验仿真，对同相型采样／保持器（S／H）进行扩展改进，提出了三种高速的二重结构S／H电路，采样速率高达30 MSPS。实验表明，在维持采样高速率的前提下，这三种电路在一定程度上解决了截止开关电流泄漏的问题，从而降低了保持电容上的电压跌落率。     

一种低电压高精度125 MHz采样/保持电路

介绍了一个低电压高精度的高速采样／保持电路。该电路的电源电压为1．8V，在125MHz频率时钟采样时，可达到10位以上的精度；采用栅源电压恒定的栅压自举开关，极大地减小了采样的非线性失真，同时，有效地抑制了输入信号的直流偏移；高性能增益自举的折叠式级联运算放大器减小了有限增益和不完全建立带来的误差。整个电路以0．18μm CMOS工艺库验证，功耗仅为11．2mW。     

新型CMOS采样/保持电路的设计研究

讨论了目前各种先进的采样／保持电路结构，基于底极板(BottomPlate)采样技术和引导开关技术，设计了一种新型的全差分开关电容双采样保持放大器，有效地消除了电荷注入和时钟馈通效应，并保证了较高的单位增益频率、采样速率和信号建立时间。电路设计基于TSMC 0．35μm CMOS工艺Bsim3模型，并采用Hspice工具对设计进行了仿真验证。     

A/D转换器AD6644在软件无线电中的应用

AD6644是一种高速度，高性能的单片14位模数转换器，它内含采样保持电路和基准源，能够精确变换宽带模拟信号（200MHz输入带宽），并具有低噪声（24dB)和低失真（100dB SFDR)特性，其采样速率可达65MSPS，信噪比的典型值为74dB。文中介绍了AD6644的主要特点和工作原理，给出了用AD6644在软件无线电接收系统中实现高速多位采样的应用电路。     

高速A/D转换器TLC5540及其应用

TLC5540是TI公司生产的高速A/D转换器。它具有75MHz模拟输入带宽并内置采样保持电路，非常适合在欠采样的情况下应用。文中介绍了TLC5540的性能指标、引脚功能、内部结构、运行时序、参考电压配置以及应用线路。     

一种用于流水线A/D转换器的低功耗采样/保持电路

文章介绍了一种适用于10位20MS／s流水线A／D转换器的采样／保持（S／H）电路。该电路为开关电容结构，以0．6μm DPDM CMOS工艺实现。采用差分信号输入结构，降低对共模噪声的敏感度，共模反馈电路的设计稳定了共模输出，以达到高精度。该S／H电路采用低功耗运算跨导放大器（OTA），在5V电源电压下，功耗仅为5mW。基于该S／H电路的流水线A／D转换器在20MHz采样率下，信噪比（SNR）为58dB，功耗为49mW。     

一种模数转换器的采样保持/增益减法电路设计

文章介绍了一种适用于算法型流水线模数转换器（Pipeline ADC）的CMOS全差分采样保持／减法增益电路的设计。该电路的工作电压为3V，在70MHz的采样频率下可达到10位以上的精度：调节型共源共栅运算放大器可在不增加更多的级联器件的情况下就可以获得很高的增益及很大的输出阻抗：专为算法型模数转换器设计的采样保持／增益减法电路通过时序控制可实现校准状态和正常转换状态的转换：通过底极板采样技术和虚拟器件有效地消除了电荷注入及时钟馈通。最后用HSPICE仿真，证明其适用于10bit及以上精度的算法型流水线模数转换器。     

Performance improvement in tensile-strained In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As metamorphic HEMT

This paper proposes a In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As (x=0.3-0.5-0.3) metamorphic high-electron mobility transistor with tensile-strained channel. The tensile-strained channel structure exhibits significant improvements in dc and RF characteristics, including extrinsic transconductance, current driving capability, thermal stability, unity-gain cutoff frequency, maximum oscillation frequency, output power, power gain, and power added efficiency.     

Morphological and electrical characterization of SixCryCzBv thin films

Si_xCr_yC_zB_v thin films with several compositions have been studied for integration of high precision resistors in 0.8 μm BICMOS technology. These resistors, integrated in the back-end of line, have the advantage to provide high level of integration and attractive electrical behavior in temperature, for analog devices. The film morphology and the structure have been investigated through transmission electron microscopy analysis and have been then related to the electrical properties on the base of the percolation theory. According to this theory, and in agreement with experimental results, negative thermal coefficient of resistance (TCR) has been obtained for samples with low Cr content, corresponding to a crystalline volume fraction below the percolation threshold.Samples with higher Cr content exhibit, instead, a variation of the TCR as a function of film thickness: negative TCR values are obtained for thickness lower than 5 nm, corresponding to a crystalline volume fraction below the percolation threshold; positive TCR are obtained for larger thickness, indicating the establishment of a continuous conductive path between the Cr rich grains. This property seems to be determinant in order to assure the possibility to obtain thin film resistors almost independent on the temperature.     

Very low-noise Al/sub 0.3/Ga/sub 0.7/As/Ga/sub 0.65/In/sub 0.35/As/GaAs single quantum-well pseudomorphic HEMTs

AlGaAs/GaInAs/GaAs pseudomorphic HEMTs with an InAs mole fraction as high as 35% in the channel has been successfully fabricated. The device exhibits a maximum extrinsic transconductance of 700 mS/mm. At 18 GHz, a minimum noise figure of 0.55 dB with 15.0 dB associated gain was measured. At 60 GHz, a minimum noise figure as low as 1.6 dB with 7.6 dB associated gain was also obtained. This is the best noise performance yet reported for GaAs-based HEMTs.<>     

A 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode array

We report a 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode (APD) array. The mean breakdown voltage of the APD was 57.9 V and the standard deviation was less than 0.1 V. The mean dark current was /spl sim/2 and /spl sim/300 nA, and the standard deviation was /spl sim/0.19 and /spl sim/60 nA at unity gain (V/sub bias/ = 13.5 V) and at 90% of the breakdown voltage, respectively. External quantum efficiency was above 40% in the wavelength range from 1.0 to 1.6 /spl mu/m. It was /spl sim/57% and /spl sim/45% at 1.3 and 1.55 /spl mu/m, respectively. A bandwidth of 13 GHz was achieved at low gain.     

Comparison between Pt/TiO2/Pt and Pt/TaOX/TaOY/Pt based bipolar resistive switching devices

Nonvolatile memories have emerged in recent years and have become a leading candidate towards replacing dynamic and static random-access memory devices. In this article, the performances of TiO₂ and TaO₂ nonvolatile memristive devices were compared and the factors that make TaO₂ memristive devices better than TiO₂ memristive devices were studied. TaO₂ memristive devices have shown better endurance performances (10⁸ times more switching cycles) and faster switching speed (5 times) than TiO₂ memristive devices. Electroforming of TaO₂ memristive devices requires~4.5 times less energy than TiO₂ memristive devices of a similar size. The retention period of TaO₂ memristive devices is expected to exceed 10 years with sufficient experimental evidence. In addition to comparing device performances, this article also explains the differences in physical device structure, switching mechanism, and resistance switching performances of TiO₂ and TaO₂ memristive devices. This article summarizes the reasons that give TaO₂ memristive devices the advantage over TiO₂ memristive devices, in terms of electroformation, switching speed, and endurance.     

Al/sub 0.3/Ga/sub 0.7/As/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) doped-channel field-effect transistors (DCFET's)

The properties of both lattice-matched and strained doped-channel field-effect transistors (DCFET's) have been investigated in AlGaAs/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) heterostructures with various indium mole fractions. Through electrical characterization of grown layers in conjunction with the dc and microwave device characteristics, we observed that the introduction of a 150-/spl Aring/ thick strained In/sub 0.15/Ga/sub 0.85/As channel can enhance device performance, compared to the lattice-matched one. However, a degradation of device performance was observed for larger indium mole fractions, up to x=0.25, which is associated with strain relaxation in this highly strained channel. DCFET's also preserved a more reliable performance after biased-stress testings.<>     

(Al/sub 0.5/Ga/sub 0.5/)/sub 0.65/In/sub 0.35/P/Ga/sub 0.65/In/sub 0.35/P double-heterostructure orange light-emitting diodes

Visible light-emitting diodes (LEDs) emitting at 615 nm and employing the AlGaInP/GaInP double heterostructure (DH) grown on a lattice-matched GaAs/sub 0.7/P/sub 0.3/ substrate have been fabricated for the first. The external quantum efficiency of 0.156% for the orange LEDs can be achieved by introducing the GaP material as the current spreader and window layer for the DH LEDs.<>     

Pseudomorphic In/sub 0.52/Al/sub 0.48/As/In/sub 0.7/Ga/sub 0.3/As HEMTs with an ultrahigh f/sub T/ of 562 GHz

We fabricated decananometer-gate pseudomorphic In/sub 0.52/Al/sub 0.48/As/In/sub 0.7/Ga/sub 0.3/As high-electron mobility transistors (HEMTs) with a very short gate-channel distance. We obtained a cutoff frequency f/sub T/ of 562 GHz for a 25-nm-gate HEMT. This f/sub T/ is the highest value ever reported for any transistor. The ultrahigh f/sub T/ of our HEMT can be explained by an enhanced electron velocity under the gate, which was a result of reducing the gate-channel distance.