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A GaAs dual-loop negative-feedback low-noise amplifier (LNA) designed for the square kilometre array is presented. Effects of transformer non-idealities on LNA performance are discussed. The LNA has 0.5 dB noise figure and -10 dB input return loss from 0.6 to 1.6 GHz. 相似文献
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提出了一款新型的复式双环电视发射天线,以屏蔽圆环天线作为复式环天线的单元天线,馈电网络采用二次补偿技术来增加天线的带宽,降低驻波比。此天线具有带宽宽、驻波低、增益高、全向性能好、成本低且结构简单等特点,很好地满足了电视发射天线的高性能要求。 相似文献
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A dual-loop phase-locked loop (PLL) for wideband operation is proposed. The dual-loop architecture combines a coarse-tuning loop with a fine-tuning one, enabling a wide tuning range and low voltage-controlled oscillator (VCO) gain without poisoning phase noise and reference spur suppression performance. An analysis of the phase noise and reference spur of the dual-loop PLL is emphasized. A novel multiple-pass ring VCO is designed for the dual-loop application. It utilizes both voltage-control and current-control simultaneously in the delay cell. The PLL is fabricated in Jazz 0.18-μm RF CMOS technology. The measured tuning range is from 4.2 to 5.9 GHz. It achieves a low phase noise of-99 dBc/Hz @ 1 MHz offset from a 5.5 GHz carrier. 相似文献
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在结构光三维(3D)重建系统中,编码模式用来解决 对应点匹配问题,将直接影响测量的精度、分辨率和 实时性。M阵列的结构光模式具有良好的子窗体特性,全局唯一。通过归纳结构光模式应遵 守的规则,利 用改进的拼片算法生成了大尺寸多元M阵列,具有2×2的子窗体特性 ,有8个阵列元素。提出符号选择 机制,采用多条件评判方法确定8个模式符号。用设计的符号代替M阵列元素,生成一种 新颖的分辨率 为1024的M阵列单 帧二值结构光模式,以减少模式的个数及规避 环境光的较强干扰。对生成的编码模式 进行的实验结果表明,利用解码算法可有效地提取生成的M阵列中的符号关键点 的信息,并实现3D目标重建,验证了本文编码模式的有效性。 相似文献
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《Solid-State Circuits, IEEE Journal of》1979,14(4):730-734
Detectable failure modes are clarified for each writing pattern. The write and erase modes for EPROM are expressed by six matrices. Four matrices express the failure modes in address, decoder and data input/output circuits, one expresses the write pattern and the last expresses bad bits in the memory array. Using this matrix method, it is clarified that the undetectable failure mode number in a 3/spl times/3 memory array is zero with a write pattern which is not a checker pattern. In addition, the failure detection rate in all `1' patterns is calculated to be about 30 percent (MNL=5) in the case of a 1 kbit memory array. 相似文献
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提出了一种基于方向图可重构天线单元的新型相控阵,并分别研究了其均匀、非均匀相控阵的扫描特性。通过重构天线单元的工作状态和各单元的激励,其均匀阵可以获得低副瓣电平等较好的辐射性能,其非均匀阵的主波束扫描范围达到±80°,在扫描平面内3dB 主波束覆盖可达176°,且栅瓣电平很低。研究表明了重构天线在相控阵天线研究中
的广阔应用前景。 相似文献
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针对任意的多输入多输出(multiple-input multiple-output, MIMO)稀疏阵列提出了MIMO单快拍成像模式和相控阵多帧联合成像模式两种三维成像方法,并对两种模式下角度分辨率及信噪比(signal noise ratio, SNR) 进行了对比. MIMO单快拍成像模式角度分辨率等价于收发联合等效阵列;相控阵多帧联合成像模式的方向图等于发射方向图与接收方向图的乘积,同样也能获得收发联合等效阵列的角度分辨率;相控阵多帧联合成像模式与MIMO单快拍成像模式的SNR的比值为发射阵列数量. 讨论了稀疏阵列与均匀满阵之间的区别与联系,稀疏阵列的波束方向图等价于均匀满阵的二维加窗快速傅里叶变换(fast Fourier transform, FFT),加窗使稀疏阵列方向图展宽. MIMO单块拍成像模式适用于对实时性要求高的应用场景,相控阵多帧联合成像模式适用于对SNR要求高的应用场景. 相似文献
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A 900-MHz monolithic CMOS dual-loop frequency synthesizer suitable for GSM receivers is presented. Implemented in a 0.50-μm CMOS technology and at a 2-V supply voltage, the dual-loop frequency synthesizer occupies a chip area of 2.64 mm2 and consumes a low power of 34 mW. The measured phase noise of the synthesizer is -121.8 dBc/Hz at 600-kHz offset, and the measured spurious levels are -79.5 and -82.0 dBc at 1.6 and 11.3 MHz offset, respectively 相似文献
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通过对双环微波光子振荡器(DMPO)的理论分析和研究,探讨了双环结构的优点和激光光源的相对强度噪声、光纤的长度以及振荡器的结构对MPO的相位噪声的影响。分析结果表明,MPO的相位噪声随着频偏的平方减小,并且与振荡频率无关;相对强度噪声越小,光纤越长,使得振荡器的相位噪声更小。分析结果可为MPO的实验研究提供理论依据。 相似文献
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提出一种基于多任务学习的共形阵列天线稀疏优化方法.该方法在考虑单元方向图的全局旋转变换和单元极化状态差异的情况下,建立了共形阵列天线导向矢量模型,结合多任务学习框架,以均匀分布共形阵列天线同一平面上阵元的方向图作为目标任务进行学习,通过稀疏向量支撑区的识别,将欠定的阵列流形矩阵方程转换为超定的特征矩阵方程进行求解,在实现阵列方向图逼近的前提下,建立了共形阵列天线阵元激励与位置联合稀疏优化的多任务学习模型.通过分块坐标下降法对稀布共形阵列天线多任务学习模型进行求解,实现了共形阵列天线的稀疏优化布阵.理论分析与实验仿真证明,该方法能有效减少共形阵的单元数量,简化共形阵列天线结构,获得与均匀分布的共形阵列天线性能一致的天线方向图,解决了稀疏共形阵列天线方向图综合优化设计难题. 相似文献
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An investigation of concentric ring antennas with low sidelobes 总被引:2,自引:0,他引:2
An analysis is made of circular antenna arrays with diameters being 2 to9lambda (the minimum inner circle diameter being0.4lambda ) containing 3 to 18 concentric circles. For the purpose of computation of the array factor the elements of the array are assumed to be isotropic radiators. The elements of each circle have equal current amplitudes and are phased so that the contributions of all the elements add in phase in the direction of the main beam. The Chebyshev radiation pattern function is approximated by a truncated Fourier-Bessel series, from which the current amplitude of each circle is obtained. From these current amplitudes a method for computing the current amplitude to excite a new distribution of fewer circles is shown. Also, an empirical method is given for improving the sidelobe level of the radiation pattern by adding an element to the center of the array. A number of circles in the array sufficient to avoid pattern deterioration is found to be the integer nearest to5d/4lambda for -20 and -30 dB sidelobe level and4d/3lambda for -40 dB, whered is the diameter of the array. This represents a large reduction in the number of circles needed over the Fourier-Bessel series representation in the case of large antennas. Experimental verification of the computed pattern is made for an array of two concentric circles with diameters of0.8lambda and1.6 at a frequency of 90 Mc/s. The elements of the array were vertical monopoles. 相似文献
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针对均匀线阵接收宽带信号产生的方向图畸变问题, 提出了一种基于Bessel权向量的宽带波束形成器.从截断后的Bessel级数展开式与均匀线阵的方向图函数相似的特性出发, 推导Bessel级数的截断位置与阵列单元数的关系, 并确定使用第一类Bessel函数设计均匀线阵的权向量.仿真结果表明:应用Bessel权向量后, 在1~3 GHz频率范围内, 均匀线阵可以无失真地接收宽带信号, 不同频率的方向图函数幅值与期望方向图函数幅值的相对误差降低到10-3以下, 且单元越多相对误差越小.与现有方法相比, 本方法直接利用截断后的Bessel级数展开式系数设计权向量, 计算简单且精度高. 相似文献
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Byungjin Chun Yong Hoon Lee Beomsup Kim 《Communications, IEEE Transactions on》1997,45(12):1520-1522
An approach to the derivation of variable loop gain sequences of dual-loop digital phase-locked loop (DPLL) is developed based on some modifications of the Kalman filtering formulation. It is shown that optimal loop gain sequences which are independent of measurement noise statistics can be obtained under a deterministic source model. Computer simulation results demonstrate that the adaptive dual-loop DPLL designed by using the proposed method is more robust to noise variations than the adaptive DPLL of Driessen (see ibid., vol.47, p.673-75, 1994) 相似文献
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讨论如何利用带约束的最大功率传输效率(CMMPTE)法通过阵列天线来综合三维方向图。通过引入测试接收阵列天线,待设计的阵列天线与之构成无线功率传输(WPT)系统,从而将方向图的综合问题转换成WPT系统功率传输效率(PTE)的优化问题。通过调整约束条件,在保证PTE最大化的条件下可获得阵列天线的激励分布,根据激励分布设计馈电网络实现近远场方向图的赋形。作为例子,设计了中心频率为2.45 GHz的赋形天线阵列,该阵列由48个微带天线单元组成,排成六棱柱形状,并在棱柱内部实现了三维圆柱形的电场赋形。 相似文献