2.3–21 GHz broadband and high linearity distributed low noise amplifier

This paper focuses on the design of a 2.3–21 GHz Distributed Low Noise Amplifier (LNA) with low noise figure (NF), high gain (S₂₁), and high linearity (IIP3) for broadband applications. This distributed amplifier (DA) includes S/C/X/Ku/K-band, which makes it very suitable for heterodyne receivers. The proposed DA uses a 0.18 μm GaAs pHEMT process (OMMIC ED02AH) in cascade architecture with lines adaptation and equalization of phase velocity techniques, to absorb their parasitic capacitances into the gate and drain transmission lines in order to achieve wide bandwidth and to enhance gain and linearity. The proposed broadband DA achieved an excellent gain in the flatness of 13.5 ± 0.2 dB, a low noise figure of 3.44 ± 1.12 dB, and a small group delay variation of ±19.721 ps over the range of 2.3–21 GHz. The input and output reflection coefficients S₁₁ and S₂₂ are less than −10 dB. The input compression point (P_1dB) and input third-order intercept point (IIP3) are −1.5 dBm and 11.5 dBm, respectively at 13 GHz. The dissipated power is 282 mW and the core layout size is 2.2 × 0.8 mm².     

过程控制中传感器静态性能指标的标准化研究

本文从标准化研究工作角度对目前过程控制中传感器重复性和线性度及总精度指标的确定中比较常见的几种方法进行了情况分析,指出从标准的角度提高过程控制中传感器重复性和线性度及总精度性能指标的科学合理的措施,进一步说明了标准的重要性。     

Ultra low voltage, high performance operational transconductance amplifier and its application in a tunable Gm-C filter

This paper presents an ultra low voltage, high performance Operational Transconductance Amplifier (OTA) and its application to implement a tunable Gm-C filter. The proposed OTA uses a 0.5 V single supply and consumes 60 μw. Employing special CMFF and CMFB circuits has improved CMRR to 138 dB in DC. Using bulk driven input stage results in higher linearity such that by applying a 500 mv_p-p sine wave input signal at 2 MHz frequency in unity gain closed loop configuration, third harmonic distortion for output voltage is −46 dB and becomes −42.4 dB in open loop state for 820 mv_p-p output voltage at 2 MHz. DC gain of the OTA is 47 dB and its unity gain bandwidth is 17.8 MHz with 20 pF capacitance load due to both deliberately optimized design and special frequency compensation technique. The OTA has been used to realize a wide tunable Gm-C low-pass filter whose cutoff frequency is tunable from 1.4 to 6 MHz. Proposed OTA and filter have been simulated in 0.18 μm TSMC CMOS technology with Hspice. Monte Carlo and temperature dependent simulation results are included to forecast the mismatch and temperature effects after fabrication process.     

A UWB CMOS low-noise amplifier with noise reduction and linearity improvement techniques

In this paper, a highly linear CMOS low noise amplifier (LNA) for ultra-wideband applications is presented. The proposed LNA improves both input second- and third-order intercept points (IIP2 and IIP3) by canceling the common-mode part of all intermodulation components from the output current. The proposed LNA structure creates equal common-mode currents with the opposite sign by cascading two differential pairs with a cross-connected output. These currents eliminate each other at the output and improve the linearity. Also, the proposed LNA improves the noise performance by canceling the thermal noise of the input and auxiliary transistors at the output. Detailed analysis is provided to show the effectiveness of the proposed LNA structure. Post-layout circuit level simulation results using a 90 nm RF CMOS process with Spectre-RF reveal 9.5 dB power gain, -3 dB bandwidth (BW_−3dB) of 8 GHz from 2.4 GHz to 10.4 GHz, and mean IIP3 and IIP2 of +13.1 dBm and +42.8 dBm, respectively. The simulated S₁₁ is less than −11 dB in whole frequency range while the LNA consumes 14.8 mW from a single 1.2 V power supply.     

基于线性输入输出关系的空间连杆机构设计

通过对机构设计要求和初始条件的分析,提出两种典型的设计方案,一种是RSSR机构,另一种是双RSSR机构。以CATIA为平台,按自顶向下的设计思路,进行空间连杆机构的结构设计,并在CATIA运动模拟机构中进行运动模拟,比较了两种方案的运动传递特性。分析指出,在输入角度较小的情况下,两种机构的输入量与输出量之间均能保持良好的线性关系;适当选择构件尺寸,双RSSR机构能基本保持输出与输入相等。而RSSR机构能否保持输出与输入相等主要受到初始条件的限制。     

ICCD在三维成像量能器读出系统中的应用

在宇宙线空间探测领域,三维成像量能器具有大几何因子和较强的粒子鉴别能力,因而具有广泛的应用前景。但是与二维量能器相比,其读出路数更多,电子学更复杂。增强电荷耦合器件(Intensified charge-coupled device,ICCD)比传统的光电器件集成度高、体积小、功耗低、发热量低,正适合用于三维成像量能器的大规模读出,改善资源利用率。本工作主要讨论了ICCD在三维成像量能器方案中的应用,介绍了ICCD线性、光强分辨率测试结果以及对串扰进行修正的方法,最后给出使用欧洲核子中心(European Organization for Nuclear Research,CERN)提供的10 GeV电子束进行束流照射实验得到的能量重建结果,初步验证了ICCD用于三维成像量能器读出系统的可行性。     

高斯核选择的线性性质检测方法*

核选择直接影响核方法的性能.已有高斯核选择方法的计算复杂度为Ω(n²),阻碍大规模核方法的发展.文中提出高斯核选择的线性性质检测方法,不同于传统核选择方法,询问复杂度为O(ln(1/δ)/ ^{2),计算复杂度独立于样本规模.文中首先给出函数 线性水平的定义,证明可使用 线性水平近似度量一个函数与线性函数类之间的距离,并以此为基础提出高斯核选择的线性性质检测准则.然后应用该准则,在随机傅里叶特征空间中有效评价并选择高斯核.理论分析与实验表明,应用性质检测以实现高斯核选择的方法有效可行.}     

脉冲涡流检测技术的研究

脉冲涡流检测技术作为当前无损检测的一种新技术,能够快速方便地检测金属导体构件中的缺陷。与传统的单频涡流技术相比,宽频谱的脉冲信号激励使得响应信号中包含了更丰富的缺陷信息。对不同深度的表面缺陷进行了检测,分析了差分信号的特征值与缺陷深度之间的关系,试验表明利用峰值不仅可以判断缺陷位置,而且还与缺陷的深度之间呈线性关系。并对一阶微分信号的特征进行了分析,结果发现,采用一阶微分信号分析可提高脉冲涡流检测系统的线性度。     

A New Test of Linearity of Time Series Based on the Bispectrum

The linearity of a time series is tested by use of the bispectrum. We define the time series to be linear if the best predictor is linear. The bispectrum is estimated by stretching the data and smoothing by the Subba Rao–Gabr optimal window. The null hypothesis tested here is that the best predictor is linear against the alternative that the best predictor is quadratic. It turns out that the test statistic is asymptotically χ²-distributed under the hypothesis that the time series is linear. The results are demonstrated using simulated and real data.