共查询到18条相似文献,搜索用时 234 毫秒
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介绍了一种利用YIG调谐滤波器锁相自跟踪技术解决因磁滞、调谐非线性、温度漂移等影响其频率准确度的方法。着重叙述了锁相自跟踪的工作原理、设计方案及预选/跟踪滤波器、锁相电路等设计技术。超外差接收前端的中频差频与YIG调谐滤波器的自跟踪技术结合可在增强射频信号预选特性的同时有效提升工作频率的准确度,此外,YIG调谐滤波器的良好线性调谐特性可使得锁相自跟踪环路在整个工作频带内具有良好的一致性。器件实测结果表明,在2~18 GHz频率范围内,频率准确度优于±1.5 MHz,方案的合理性和技术的先进性对YIG调谐滤波器在高性能电子设备中的应用有较大的参考意义和实用价值。 相似文献
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用单晶铁氧体谐振器替代普通微波滤波器的分布参数谐振器构成滤波器。介绍了单晶铁氧体谐振器工作原理,给出了单晶小球的谐振等效电路及其Q值计算式,利用其铁磁共振原理,实现滤波器的多倍频程宽频带磁调谐。用传统滤波器设计方法,基于磁耦合带阻滤波器的工作原理并通过两次滤波器电路的简化,设计出单晶铁氧体带阻滤波器通带,给出了电路的仿真曲线。利用低通滤波器电感环球耦合,成功实现带阻滤波器的磁耦合结构,用单晶铁氧体带通滤波器设计方法设计带阻滤波器阻带调谐结构并给出了环球的结构参数。最后给出了滤波器的实测曲线,在0.5~2GHz通带内插损<2dB,电压驻波比小于2,阻带最小40dB带宽>8MHz,最大3dB带宽<150MHz,阻带深度>60dB。 相似文献
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依据YIG调谐限幅滤波器的工作原理,设计了一款S波段限幅滤波器。对滤波器进行了连续波限幅特性和抗烧毁功率测试,在S波段下,滤波器的限幅电平大于5 dBm,常温下最大为8 dBm;连续波输入情况下,滤波器的限幅输出功率小于10 dBm,为6.5 dBm;滤波器的抗烧毁功率大于50 W连续波,当脉冲输入峰值功率从2 W到200 W范围内变化时,滤波器的输出脉冲峰值功率被限制在18.5 dBm内,起到了很好的限幅滤波作用。试验证明设计的S波段YIG限幅滤波器不仅宽频段可调,具有良好的滤波特性,对高功率输入信号限幅输出,用于接收系统前端可有效保护后续电路的安全。 相似文献
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将半集中参数的环耦合电路等效为截止频率很高的低通滤波器作为直通传输,YIG小球在外场的作用下等效为一个可变的L-C谐振回路,和低通滤波器叠加形成一个阻带中心频率可调的带阻滤波器.给出2~18GHz、16级等元件结构YIG调谐带阻滤波器的实验结果,该滤波器的直通损耗小于2dB,阻带高度大于40dB, 40dB阻带宽度大于8MHz,已达到实用水平. 相似文献
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基于偏置环形谐振器和加载电容器的缺陷地结构设计了一种具有宽上阻带和双陷波的超宽带滤波器。利用奇偶模分析法分析三阶接地短截线的传输极点与结构的对应关系,得到了一个具有五个传输极点的结构。通过采用三阶接地短截线结构和偏置环形谐振器的级联结构得到通带和宽上阻带,通带范围为2.95~12.24 GHz,相对带宽达到122%,上阻带大于10 dB,衰减范围至28.04 GHz。引入两个相同的H形缺陷地结构,并且在缝隙处焊接电容器,在2.69 GHz处共同产生传输零点来改善滤波器带外抑制特性。使用两个不同尺寸的半H形缺陷地结构分别在5.64 GHz和8.31 GHz处产生陷波,陷波衰减分别为16 dB和20 dB,提高滤波器的抗干扰能力。 相似文献
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波导带通滤波器的设计 总被引:3,自引:0,他引:3
高葆新 《国外电子测量技术》2001,(1):34-37
波导带通滤波器是一种选频电路,应用在通信、电子战(EW)、雷达、自动测量设备(ATE)等的微波设备中。它易与波导天线的馈电装置连接。适于高功率的应用并且性能良好,在小信号电平上,它基本上是用在8到100GHz的频率范围,波导滤波器的主要功能是通带插入损耗和失真很小的前提下,提供足够的阻带选择性。例如,在微波接收机中,波导带通滤波器滤掉不需要的带外信号,保持前端噪声特性。在微波发射机中,减小不需要的频谱,抑制发射机噪声传到接收机。波导带通滤波器还应用在各种微波多工器上,本文对波导带通滤器的设计、研制和制造的关键技术进行了讨论。 相似文献
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在深水隔水管监测系统上,为了接收水下节点发射的信号,研究设计了一款低噪声低功耗水下接收机。在海洋环境下,由于发射机发射功率,传播损失以及传播过程中噪声干扰等影响,造成接收信号畸变、衰减、动态范围增大等问题,不利于后端数字处理。本系统选择低噪声芯片,优化电路结构、降低系统噪声,通过六阶椭圆滤波器,选择所需频带信号通过,采用AGC实现大动态范围的压缩。海试结果显示,该系统具有高灵敏度、低噪声、低功耗、接收动态范围大等优点。 相似文献
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基于语音信号的A律或μ律非线性量化方法,由于其先采用一个线性转换器进行量化,再用数字硬件或软件量化为A律或μ律电平。其为:用较少的二进制位代替较多二进制位的数字压缩编码。在动态范围更大的非语音信号采集中,常被误认为可以用此法来"扩展小信号的可量化范围",因前线性转换器的量化台阶决定了其最小信号分辨率,这里的问题主要在:信号的量化前后处理意义不同。要扩展小信号的量化范围,在A/D转换的位数一定情况下,为保证输入峰值不超载,应该对其输入的模拟信号进行A律或μ律折线非线性放大处理。 相似文献
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Ajinkya Kale Johannes Sturm Vijaya Sankara Rao Pasupureddi 《International Journal of Circuit Theory and Applications》2019,47(4):549-560
In this work, a reconfigurable multistandard subsampling receiver with dynamic carrier frequency detection and system-level EVM optimizations is proposed. Ideal software defined radio (SDR) receivers promise complete flexibility at the expense of high-performance analog-to-digital converters (ADCs) that are challenging to implement in current technologies for low-power applications. This scenario leads to the research of digital intensive sampling receivers with discrete-time signal processing (DTSP) implemented in analog domain. This approach makes it feasible to move channel selection filtering and dynamic gain adaptability from analog to digital domain. The proposed receiver employs subsampling down-conversion along with subband filters to dynamically detect the carrier frequency of the incoming signal, estimate its bandwidth, and identify if the signal is present in one of the target standard bands. This carrier detection provides a unique capability to reconfigure the receiver dynamically. Additionally, in this work, system-level EVM optimization is proposed considering frequency synthesizer phase noise, IQ mismatch, sampling frequency selection and block-level gain, noise, and nonlinearity. The RF front end of the proposed receiver is modeled in Verilog-AMS whereas the digital signal processing is implemented in Simulink-Matlab. The complete receiver has been verified to detect and process three different bands belonging to three different standards (GSM, UMTS, and WLAN) with the carrier frequency ranging from 0.9 to 2.5 GHz. Test signals with 4-QAM modulation, maximum bandwidth of 20 MHz, and input-dynamic range from –109 to –20 dBm is utilized to demonstrate the receiver performance including an EVM of –40 dB. 相似文献
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主瓣干扰一直是雷达抗干扰技术难以解决的问题.实验发现常规幅相重构算法对非恒模干扰的抑制效果不好.针对主波束方向的压制性强干扰,采用滑窗改进的幅相重构算法进行抑制.即使干扰不完全具备恒模特征,也可以通过细化采样窗长估计此采样窗口内所有采样点的干扰幅度,然后每次滑动窗口估计下一个采样点的幅度信息,并且利用接收信号的单位向量逐点估计相位信息,及时解析重构干扰信号,最后从雷达接收的和信号中将重构得到的干扰消去,从而达到抑制主瓣干扰的目的.仿真实验获得较理想的干扰相消效果,此方法对雷达抗干扰能力的提升具有重要的意义. 相似文献
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Micropower CMOS Integrated Low-Noise Amplification, Filtering, and Digitization of Multimodal Neuropotentials 总被引:1,自引:0,他引:1
Mollazadeh M. Murari K. Cauwenberghs G. Thakor N. 《IEEE transactions on biomedical circuits and systems》2009,3(1):1-10
Electrical activity in the brain spans a wide range of spatial and temporal scales, requiring simultaneous recording of multiple modalities of neurophysiological signals in order to capture various aspects of brain state dynamics. Here, we present a 16-channel neural interface integrated circuit fabricated in a 0.5 mum 3M2P CMOS process for selective digital acquisition of biopotentials across the spectrum of neural signal modalities in the brain, ranging from single spike action potentials to local field potentials (LFP), electrocorticograms (ECoG), and electroencephalograms (EEG). Each channel is composed of a tunable bandwidth, fixed gain front-end amplifier and a programmable gain/resolution continuous-time incremental DeltaSigma analog-to-digital converter (ADC). A two-stage topology for the front-end voltage amplifier with capacitive feedback offers independent tuning of the amplifier bandpass frequency corners, and attains a noise efficiency factor (NEF) of 2.9 at 8.2 kHz bandwidth for spike recording, and a NEF of 3.2 at 140 Hz bandwidth for EEG recording. The amplifier has a measured midband gain of 39.6 dB, frequency response from 0.2 Hz to 8.2 kHz, and an input-referred noise of 1.94 muV rms while drawing 12.2 muA of current from a 3.3 V supply. The lower and higher cutoff frequencies of the bandpass filter are adjustable from 0.2 to 94 Hz and 140 Hz to 8.2 kHz, respectively. At 10-bit resolution, the ADC has an SNDR of 56 dB while consuming 76 muW power. Time-modulation feedback in the ADC offers programmable digital gain (1-4096) for auto-ranging, further improving the dynamic range and linearity of the ADC. Experimental recordings with the system show spike signals in rat somatosensory cortex as well as alpha EEG activity in a human subject. 相似文献