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Arjuna Madanayake H.L.P. Bruton L.T. 《IEEE transactions on circuits and systems. I, Regular papers》2008,55(6):1546-1559
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本文设计出了一种既能产生针状波束又能产生扇形波束的新型面天线,该天线的增益和方向图通过理论计算计算出来。本文设计实例中的面天线的针状波束的E、H平面的半功率宽度分别为2.320、2.240,而扇形波束的E、H平面的半功率宽度分别为2.010,6.40。 相似文献
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两输入全差分高频宽线性可调的OTA及其滤波器应用 总被引:3,自引:0,他引:3
文章提出了一种采用两输入全差分结构、线性可调范围宽的高频跨导运算放大器,适合于需大范围连续调谐的高频连续时间滤波器。仿真结果表明,通过频率补偿,在高频情况下,它不仅具有良好的线性输入和线性可调范围,而且具有较好的频率响应特性,对高频滤波器的性能有一定的改善。 相似文献
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Dattaguru V. Kamat P. V. Ananda Mohan K. Gopalakrishna Prabhu 《Circuits, Systems, and Signal Processing》2010,29(3):553-576
In this paper, a general structure using dual-output operational transconductance amplifiers (OTAs) is explored to derive
new first-order and second-order multi-function filters using OTAs with multiple current outputs and with and without grounded
capacitors. Two first-order all-pass filters that have been obtained are presented, together with an analysis of nonidealities
of OTAs, viz., finite bandwidth and parasitic output and input resistance and capacitance. Second-order multi-function filters
obtained by using OTA-C simulated inductances in the proposed general structure are also presented. The realization of quadrature
oscillator using the proposed first-order all-pass networks is also considered. Detailed analysis of nonideal frequency performance
of the OTAs as well as finite output and input impedances is presented. SPICE simulation results are also given for the proposed
circuits. 相似文献
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Zhu Weiping 《中国邮电高校学报(英文版)》1995,(1)
AVeryEfficientApproachfortheSynthesisof2-DRecursiveFanFiltersZhuWeiping(DepartmentofTelecommunicationEngineering,NanjingUnive... 相似文献
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A new, low-cost, switched-beam and fully adaptive antenna array suitable for 2.4 GHz ISM applications is proposed in this paper. The array comprises of four elements, equal in number receiving RF and IF components, as well as a microcontroller based unit which is responsible for the control of the array. The array is designed with the aid of a custom genetic algorithm, while measurements results are presented indicating consistency between design and implementation. In addition, multipath fading mitigation capability of the array is demonstrated via channel measurements results. 相似文献
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A convolutional backprojection algorithm is derived for a fan beam geometry that has its center-of-rotation displaced from the midline of the fan beam. In single photon emission computed tomography (SPECT), where a transaxial converging collimator is used with a rotating gamma camera, it is difficult to precisely align the collimator so that the mechanical center-of-rotation is colinear with the midline of the fan beam. A displacement of the center-of-rotation can also occur in X-ray CT when the X-ray source is mispositioned. Standard reconstruction algorithms which directly filter and backproject the fan beam data without rebinning into parallel beam geometry have been derived for a geometry having its center-of-rotation at the midline of the fan beam. However, in the case of a misalignment of the center-of-rotation, if these conventional reconstruction algorithms are used to reconstruct the fan beam projections, structured artifacts and a loss of resolution will result. We illustrate these artifacts with simulations and demonstrate how the news algorithm corrects for this misalignment. We also show a method to estimate the parameters of the fan beam geometry including the shift in the center-of-rotation. 相似文献
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《IEEE transactions on circuits and systems. I, Regular papers》2008,55(7):1953-1966
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《IEEE transactions on medical imaging》2008,27(12):1791-1810
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Bluetooth is a specification for short‐range wireless communication using the 2.4 GHz ISM band. It emphasizes low complexity, low power, and low cost. This paper describes an area‐efficient digital baseband module for wireless technology. For area‐efficiency, we carefully consider hardware and software partitioning. We implement complex control tasks of the Bluetooth baseband layer protocols in software running on an embedded microcontroller. Hardware‐efficient functions, such as low‐level bitstream link control; host controller interfaces (HCIs), such as universal asynchronous receiver transmitter (UART) and universal serial bus (USB) interfaces; and audio Codec are performed by dedicated hardware blocks. Furthermore, we eliminate FIFOs for data buffering between hardware functional units. The design is done using fully synthesizable Verilog HDL to enhance the portability between process technologies so that our module can be easily integrated as an intellectual property core on system‐on‐a‐chip (SoC) ASICs. A field programmable gate array (FPGA) prototype of this module was tested for functional verification and realtime operation of file and bitstream transfers between PCs. The module was fabricated in a 0.25‐µm CMOS technology, the core size of which was only 2.79 mm×2.80 mm. 相似文献
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The need and advantages of lossy elements in unconditional EMC filter design are well recognized. This paper describes a lossy device based on the proximity effect using multilayer strip lines. Expressions are derived for the losses in the multilayer strip conductors. Experimental data show good agreement with theoretical expectations when the differences between the theoretical model and actual implementations are taken into account. The formula for an infinite stack provides a theoretical upper limit to the losses as a function of frequency. A modified empirical formula provides a practical design equation. Applications are also discussed. 相似文献
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A first-order Markov process is used to model the sequence of quantization noise samples in delta modulation. An autocorrelation parameterC in the Markov model controls the shape of the noise spectrum, and asC decreases from 1 to 0 and then to -1, the spectrum changes from a low-pass to a flat, and then to a high-pass characteristic. One can also use the Markov model to predict the so-called out-of-band noise rejection that is obtained when delta modulation is performed with an oversampled input, and the resulting quantization noise is lowpass filtered to the input band. The noise rejectionG is a function ofC as well as an oversampling factorF and an interesting asymptotic result is thatG=frac{1-C}{1+C} dot F ifF gg frac{1+C}{1-C} dot frac{pi}{2} . Delta modulation literature has noted the importance of the specialG values,F and2F . These correspond to autocorrelation values of 0 and -1/3. 相似文献
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María J. Avedillo José M. Quintana Hamid El Alami Antonio Jiménez-Calderón 《The Journal of VLSI Signal Processing》2004,38(2):91-100
Stack filters belong to the class of non-linear filters and include the well-known median filter, weighted median filters, order statistic filters and weighted order statistic filters. Any stack filter can be implemented by using the parallel threshold decomposition architecture which allows implementing their non-linear processing by means of a collection of identical binary filters (Boolean logic circuits). Although it is conceptually simple and useful to study the filter properties, this architecture is not practical for direct hardware implementation because as many as (M – 1) binary filters are required for a M-valued input signal and M is large in many applications.In this paper we introduce a new parallel architecture for stack filter implementations. The complexity is now proportional to the window width L of the filter, instead of to M. In most applications L is much smaller than M which translates into efficient hardware implementations. The attractive characteristic of ease of design exhibited by the threshold decomposition architecture is kept. In fact, for a given stack filter both in the conventional implementation and in the proposed one, the same binary filter is required. The key concept supporting the new architecture is a modified decomposition scheme which generates L binary signals for a multi-valued input. As an application example, a complex WOS filter is designed and prototyped in an FPGA. 相似文献
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A maximum likelihood receiver for an orthogonally multiplexed QAM (OQAM) system has been derived based on the mathematical structure of an OQAM signal. The resulting receiver provides the minimum variance estimates of carrier and timing phases under the disturbance caused by not only Gaussian noise but also random data. It has also been proven that the carrier and timing joint control system is asymptotically stable almost everywhere in a state space. The equilibrium points are where the parallel synchronization over all subchannels in the OQAM system is established. Simulations have been carried out in order to verify the maximum likelihood receiver performances, where 9600 bit/s data are transmitted over 750-2450 Hz voiceband with 8×8 staggered QAM signal constellations. It has been shown that sufficient eye opening is obtained under 10 Hz carrier frequency offset and 10-4timing frequency stability. 相似文献
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An improved first-order approximate decorrelating detector for direct-sequencecode divisionmultiple access (DS-CDMA) communication systems is proposed. This detector isbased on theminimization of the multiple access interference (MAI) for each user. Throughanalysis andnumerical results, the detector is shown to perform better than the originalfirst-order approximatedetector in various conditions at the expense of an additional complexity onthe order of O(K2), whereK is the number of active users in the system. 相似文献
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针对A/D转换器中广泛使用的Flash单元,设计了一组由全差分预放大器、动态比较器和D触发器组成的电路。对电路的抗翻转噪声能力进行了分析和仿真,指出,通过改进全差分预放大器的共模反馈电路,有效提高了Flash单元抗翻转噪声的能力。利用SMIC 0.18μm CMOS混合信号工艺,将设计的Flash单元应用到一个Flash A/D转换器中进行了流片。A/D转换器具有100 MHz奈奎斯特采样带宽。流片测试结果表明,采用该Flash单元的A/D转换器的信噪比SNR获得了改善,有效位数ENOB能提高大约0.6比特。 相似文献