共查询到18条相似文献,搜索用时 125 毫秒
1.
提出了一种基于锁相环(Phase-locked Loop,PLL)与直接数字合成(Direct Digital Synthesis,DSS)等技术相结合的高场核磁共振波谱仪频率合成器设计方案.该系统以单片机为控制器完成算法运行、参数配置和CAN总线通信功能,运用PLL技术和DDS技术相结合的频率合成方案,通过两次混频,使频率粗调和细调灵活可控,实现宽带低噪声频率输出.将该频率合成器用于自主研制开发的核磁共振波谱仪上进行实验验证,测试得到的线形和灵敏度均达到指标要求,结果证明该设计方案具有可行性. 相似文献
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提出了一种基于锁相环(Phase-locked Loop, PLL)与直接数字合成(Direct Digital Synthesis, DSS)等技术相结合的高场核磁共振波谱仪频率合成器设计方案.该系统以单片机为控制器完成算法运行、参数配置和CAN 总线通信功能,运用PLL 技术和DDS 技术相结合的频率合成方案,通过两次混频,使频率粗调和细调灵活可控,实现宽带低噪声频率输出.将该频率合成器用于自主研制开发的核磁共振波谱仪上进行实验验证,测试得到的线形和灵敏度均达到指标要求,结果证明该设计方案具有可行性. 相似文献
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Pound-Drever-Hall(PDH)稳频方法涉及光学和电学2个部分,综合仿真较为困难。针对该问题,设计了PDH的电路部分。根据器件的工作原理,采用电路模型搭建光学元件。在此基础上进行了器件的单独仿真和开环PDH光、电综合仿真,仿真使用长度为15 cm,腔镜反射率为0.97的Fabry-Pérot腔(F-P腔),并采用20 MHz的调制频率。仿真结果表明:器件模型搭建合理;激光器在无频率漂移时,系统输出较小幅度的零漂移信号;在频率漂移为5 MHz,10 MHz,15 MHz时,系统输出较为理想的误差信号。最后对仿真结果进行了讨论,并提出了改进方案。 相似文献
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介绍了一种应用于核磁共振(Nuclear Magnetic Resonance,NMR)波谱仪的宽频带射频功率放大器的设计与实现,提出了射频功率放大器门控信号的设计,探讨了利用传输线变压器构建功率MOSFET输入输出阻抗匹配网络的方法. 该射频功率放大器采用多级驱动结合功率放大的结构,包含2个工作模块和基于宽频带定向耦合器的辅助电路,支持高带和宽带通道的相关实验. 将该射频功率放大器应用在自主研发的500 MHz高分辨率液体NMR谱仪上,测量射频功放的上升、下降时间及输出线性度,并对比测试1H和13C NMR标样的信噪比,实验结果证明了该设计的可行性. 相似文献
6.
介绍了一种极化正交全耦合型高功率微波(HPM)合成器,其主要用途是实现两路HPM分时共用一个天线辐射.合成器主要由输入段、耦合段及输出段三部分组成,利用该合成器能够实现一个吉瓦级HPM脉冲序列和一个百兆瓦级HPM脉冲序列由一个公共端口共同输出.合成器输入段有与主通道及副通道相连的两个输入端口,合成器的主通道与公共输出口直接相连,副通道利用连续长缝结构将能量耦合进入主通道经公共输出口输出.利用数值模拟方法对合成器进行了优化设计,合成器主通道的能量传输效率可达99%以上,副通道的能量耦合效率可达96%以上.建
关键词:
高功率微波
合成器
耦合波 相似文献
7.
数字化和小型化是铷原子频标(RAFS)发展的重要方向.在传统铷原子频标电路中,6 840 MHz微波信号与频率综合器产生的5.312 5 MHz信号进行混频,得到用于激励铷原子跃迁的6 834.687 5 MHz微波探寻信号.早期铷频标的频率综合器大量使用了分立的模拟器件,数字化程度低、参数优化工作繁杂、电路体积较大.目前常用直接数字频率合成器(DDS)方案直接产生5.312 5 MHz信号,但这种数字电路方案通常需要对10 MHz信号进行倍频,它存在频谱纯度较低、相位噪声高等缺点.本文介绍一种产生5.312 5 MHz信号的频率综合器解决方案,这种设计方案在应用DDS器件时无需使用10 MHz倍频电路,它具有频谱纯度较高、相位噪声低、输出频率和相位可调等优点. 相似文献
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In this paper, an approach of developing high performance millimeter-wave frequency synthesizer is proposed, which is significantly
simpler than the conventional cases. The synthesizer is driven by one triple tuned typed synthesizer, which adjusts the output
frequency of DDS and frequency division ratios of variable frequency divider to suppress the spurious level. With the proposed
method, a microwave phase locked loop (PLL) PE3236 and a millimeter-wave multiplier HMC283 are also used. Moreover, the PLL
is implemented with the form of charge pump followed by a passive three-order low-pass filter which can further suppress the
phase noise. Finally, a low spurious level and high frequency resolution millimeter-wave frequency synthesizer without degradation
of frequency switching speed is developed. Experimental results show that this method can achieve the performances of low
spurious level, low phase noise, and high frequency resolution. 相似文献
12.
R. W. McMillan S. M. Sharpe J. Seals M. G. Elis M. L. Studwell V. T. Brady E. C. Burdette 《International Journal of Infrared and Millimeter Waves》1986,7(9):1259-1280
This paper describes a millimeter wave frequency synthesizer based on a single broadband backward wave oscillator tube which is capable of covering the entire 40–60 GHz waveguide band with useful power output, low phase noise, and rapid frequency switching. The synthesizer is controlled by an internal microcomputer which sets the reference oscillator frequency through a General Purpose Interface Bus (GPIB) and generates synthesizer coarse tuning corrections through a programmable digital-to-analog converter. The phase/frequency control system uses a frequency discriminator for capture of the source from large frequency errors and a complementary phase lock for precise phase and frequency control. 相似文献
13.
Wenqin Wang 《International Journal of Infrared and Millimeter Waves》2006,27(11):1433-1444
In remote sensing applications, there is a special interest in the lightweight, cost effective, and high resolution imaging
sensors. The combination of linearly frequency modulated continuous wave (LFMCW) technology and synthetic aperture radar (SAR)
technique can lead to such a sensor. This paper concentrates on the analysis of waveform errors in millimeter-wave (MMW) LFMCW
SAR. The generating scheme of millimeter-wave LFMCW waveforms with phase locked loop (PLL) and direct digital synthesizer
(DDS) combined frequency synthesizer is investigated. The impacts of quantization errors, spurs, and frequency nonlinearities
are analyzed. Simulation results show that the quality of LFMCW waveforms has a direct influence on the SAR images. Hence
a scheme of frequency synthesizer to achieve high performance MMW LFMCW waveform is proposed. This synthesizer driven by a
DDS array can adaptive suppress the spurious level without degradation of excellent frequency linearity and fast switching
speed. 相似文献
14.
A sweep optical frequency synthesizer is demonstrated by using a frequency-stabilized optical frequency comb and injection-locked distributed-Bragg-reflector (DBR) laser diode. The injection-locked DBR laser acts as a single-frequency filter and, simultaneously, a high-gain amplifier of the optical frequency comb. The frequency instability of the heterodyne beat signal between two independently injection-locked DBR lasers is measured to be 2.3 x 10(-16) at 1 s averaging time. The output frequency of the sweep optical frequency synthesizer can be precisely tuned over 1 GHz, and a saturated absorption spectrum of the Cs D2 line at 852 nm is recorded by the injected DBR laser. 相似文献
15.
介绍了直线加速器高频全固态功率源中大功率合成器件-3 dB定向耦合器的理论计算和工程设计过程, 该合成器工作频率80.5 MHz, 输出连续波功率大于20 kW。 分析了合成器的功率容量, 并对相应的理论计算结果、 CST (Computer Simulation Technology)软件模拟计算结果和实际功率合成器件测量结果进行了比较。 通过比较得出, CST仿真结果与测试结果基本一致, 隔离度和电压驻波比等实测指标优于设计指标, 只有耦合度与设计指标有些偏差, 总体上达到了预期的设计要求。 在输出功率20 kW时, 取样波形无失真, 合成器无明显温升, 满足固态功率源大功率稳定运行的要求。 The principle of design and calculation of the power synthesis in the solid state amplifier are described in this paper. The working frequency of the synthesizer is 80.5 MHz. The output continuous wave power is more than 20 kW; The synthesizer power capacity is analyzed. The theoretical calculation results, Computer Simulation Technology (CST) simulated results are compared with the measured results of the actual 3 dB couplers. The analysis of the measured results and CST calculated results shows that the simulation is in agreement with the measurement results which meet the design requirements of the solid state amplifier. Except the coupling coefficient, the isolation, the VSWR and other parameters are better than the design target. When the output power is 20 kW, the sampling waveform has no deform and the temperature of the synthesizer is stable. 相似文献
16.
Pinpin Yan Wei Hong Jixin Chen 《International Journal of Infrared and Millimeter Waves》2008,29(3):282-290
A millimeter wave phase locked and frequency multiplying source is proposed in this paper. The design includes an X-band phase
locked loop (PLL) frequency synthesizer as the base frequency source, and a monolithic millimeter wave frequency tripler,
which is developed by using OMMIC 0.18μm pHEMT process. The PLL and the tripler are integrated in a single circuit board to
make a low-cost and compact frequency source with the size of 6cm × 5cm. Measurement shows an output power of more than 4.8dBm
at the frequency range from 35 to 36.7GHz. A phase noise of about -92dBc/Hz at 100kHz offset is achieved. 相似文献
17.
Daussy C Lopez O Amy-Klein A Goncharov A Guinet M Chardonnet C Narbonneau F Lours M Chambon D Bize S Clairon A Santarelli G Tobar ME Luiten AN 《Physical review letters》2005,94(20):203904
We use a new technique to disseminate microwave reference signals along ordinary optical fiber. The fractional frequency resolution of a link of 86 km in length is 10(-17) for a one day integration time, a resolution higher than the stability of the best microwave or optical clocks. We use the link to compare the microwave reference and a CO2/OsO4 frequency standard that stabilizes a femtosecond laser frequency comb. This demonstrates a resolution of 3 x 10(-14) at 1 s. An upper value of the instability introduced by the femtosecond laser-based synthesizer is estimated as 1 x 10(-14) at 1 s. 相似文献
18.
F. Hindle G. Mouret S. Eliet M. Guinet A. Cuisset R. Bocquet T. Yasui D. Rovera 《Applied physics. B, Lasers and optics》2011,104(4):763-768
The generation of cw-THz radiation by photomixing is particularly suited to the high resolution spectroscopy of gases; nevertheless,
until recently, it has suffered from a lack of frequency metrology. Frequency combs are a powerful tool that can transfer
microwave frequency standards to optical frequencies and a single comb has permitted accurate (10−8) THz frequency synthesis with a limited tuning range. A THz synthesizer composed of three extended cavity laser diodes phase
locked to a frequency comb has been constructed and its utility for high resolution gas phase spectroscopy demonstrated. The
third laser diode allows a larger tuning range of up to 300 MHz to be achieved without the need for large frequency excursions,
while the frequency comb provides a versatile link to be established from any traceable microwave frequency standard. The
use of a single frequency comb as a reference for all of the cw-lasers eliminates the dependency of synthesized frequency
on the carrier envelope offset frequency. This greatly simplifies the frequency comb stabilization requirements and leads
to a reduced instrument complexity. 相似文献