数字伺服实现相干布居囚禁原子频标的激光稳频

介绍了为实现小型化相干布居囚禁(CPT)原子频标的激光频率锁定,用以现场可编程门阵列(FPGA)为核心的数字控制电路将激光频率锁定在多普勒吸收峰的工作.以同样的控制方法将微波频率锁定在电磁感应透明(EIT)峰上之后,实现了CPT原子频标样机整机锁定.基于FPGA用Verilog语占实现的CPT原子频标数字伺服系统具有电路结构清晰紧凑、参数设置更改方便、程序查错容易、功耗低、温度系数小等优点.受益于语言编写及数字电路的特点,系统具有移植性和一致性好的优点.所研制出的CPT频标样机功耗4 W,稳定度达到6×10-11τ-1/2,表明该数字伺服电路方案是可行的.     

基于85Rb的微型化CPT原子钟的设计和实现

介绍基于85Rb原子相干布居囚禁(CPT)现象的微型原子钟的设计与实现,系统以MSP430单片机作为主控芯片,实现电流源、TCXO和射频等功能模块,并与CPT原子钟物理部分实现联调与整机封装,实现了高稳定度、低功耗的小型CPT原子钟。整机体积只有31 cm3,功耗为660 mW,测得10 MHz输出信号稳定度约为2×10-10 s-1,4×10-11/1 000 s。系统采用全宽调制在85Rb的D1线实现CPT原子钟方案,可提升CPT共振谱线对比度,提高原子钟稳定度。     

低功耗、小型化稳频激光系统的设计与实现

设计并实现了一种低功耗、小型化、可长期稳定运行的自动稳频激光系统。通过设计并实现高效率、低纹波的电压源,较大幅度地降低了整个系统的功耗和体积;通过设计并实现高性能温度控制电路、电流控制电路和稳频电路,得到了线宽较窄、频率稳定度较高的输出激光。该系统能够自动长期稳频,输出激光线宽约为1 MHz,稳定度指标为秒稳定度1.43×10~(-10),十秒稳定度3.90×10~(-11),百秒稳定度1.28×10~(-11),千秒稳定度2.25×10~(-11)。在稳定度略优于商用外腔半导体激光器的前提下,该激光系统电源体积缩小了约85%,整机功耗降低了约90%,为实现半导体稳频激光系统的低功耗和小型化提供了一种新的方案。     

基于ADN8830的非制冷红外焦平面温度控制电路设计

这里利用AD公司的热电制冷控制器ADN8830设计出高性能、高稳定性的TEC控制电路.该电路通过简单的电容、电阻构成的外部PID(比例积分微分)补偿网络,能够使探测器温度在10 s内稳定在最佳工作点,温度控制精度可达0.01 ℃.实验结果表明该方案具有效率高、功耗低、体积小等优点,是一种较好的温控设计方案.     

CPT铷原子钟微波信号源设计

CPT原子钟由于其体积小、重量轻、功耗低等优点,广泛应用于通信、导航及数据传输等领域。设计基于数字锁相倍频技术,采用锁相环芯片ADF4350,根据CPT铷原子钟的需求实现了一种中心频率为3417MHz的微波信号源。经测试,信号源电路尺寸为30mm×30mm,功耗小于150mW,输出微波功率范围为(-20～-5)dBm,输出信号相位噪声与理论分析相符,杂散抑制满足设计要求,可用于CPT铷原子钟。     

高精度低噪声集成温度补偿晶体振荡器

介绍了一种新的AT切低噪声集成温度补偿晶体振荡器(TCXO)的设计方案、补偿原理及实现.该设计核心是采用电路集成实现器件的小体积、低功耗,并通过模数混合集成工艺,保证温补晶振的高精度和低相噪特性.实验样品在-40~+85 ℃的温度范围内,频率温度稳定度优于±2.8×10-7,相位噪声达到-140 dBc/Hz@1 kHz.测试结果表明,该集成温度补偿晶体振荡器具有工作温度范围宽,补偿精度高,功耗低,频谱纯度高,噪声特性良好等特点.同时,该温度补偿晶体振荡器集成度高,体积小,抗振动冲击,适合大批量生产,可广用于军民用测控通信系统中.     

星载MEMS原子钟稳频系统的优化及实验研究

简要介绍CPT原子钟工作原理,讨论原子频标的两个重要指标:短期稳定性和频率漂移.对CPT原子钟的锁频伺服控制电路进行系统分析和优化设计,并通过饱和吸收稳频实验验证所设计伺服控制电路的稳频性能,100 s的频率稳定度达到1.6×10-12,有望进一步提高频率稳定性.     

非制冷焦平面热像仪温度控制设计

在分析法国ULIS公司生产的320×240长波红外非制冷微测辐射热计焦平面阵列探测器UL01011技术参数的基础上,论述了微测辐射热计非制冷红外焦平面热像仪温度控制的必要性,指出了温度控制设计的实质。并讨论了单片机、线性模式单芯片热电制冷器控制器和开关模式单芯片热电制冷器控制器温控方案的优缺点。提出了使用AD公司生产的全新单芯片热电制冷器控制器ADN8830的温控设计方案,以该芯片为核心设计出适合320×240长波红外非制冷微测辐射热计焦平面阵列探测器UL01011的温度控制电路,该电路能够把焦平面阵列温度变化控制在30±0.01℃范围内,使探测器工作在最佳温度。该方案功耗低、效率高、体积小,是一种较好的温控设计方案。     

DPSSL激光器的高精度温控电路设计与实现

针对温度变化对于DPSSL激光器工作波长及稳定性的影响问题,提出了一种基于TEC和专用控制芯片LTC1923的温控方案,设计了温控电路及其保护电路,实现了DPSSL工作温度的精确控制。首先分析了DPSSL温控指标需求和TEC热电制冷原理,阐述了温控系统组成及原理;然后详细介绍了温控电路及其保护电路的设计,讨论了防电磁干扰措施及注意事项;最后针对某型DPSSL激光器负载,测试了温控系统的稳态误差、超调量等指标;实验数据显示,该温控系统稳态误差小,控制精度达±0.01℃,能保证DPSSL高稳定性工作。     

高稳双层恒温晶振的设计

为了提高晶体振荡器的温频特性,设计了双层恒温高稳定度晶体振荡器。振荡器温控系统采用双层控温结构,通过多点加热和多点感温的方式,改进了恒温槽的设计,极大地改善了产品的频率温度稳定度。同时电路采用SC切晶体谐振器和Colpitts电容三点式振荡电路,提高了产品的短期频率稳定度。通过实际测试,该振荡器温度-频率特性和短期频率稳定度分别达到<±2E ^-10(-30~+70 ℃)和<1E ^-12/s的指标,均比同类产品提高1个量级以上,同时其老化率指标可达<5E ^-11/日。     

星载MEMS原子钟稳频系统的优化及实验研究

简要介绍CPT原子钟工作原理,讨论原子频标的两个重要指标：短期稳定性和频率漂移。对CPT原子钟的锁频伺服控制电路进行系统分析和优化设计,并通过饱和吸收稳频实验验证所设计伺服控制电路的稳频性能．100s的频率稳定度达到1．6×10^-12,有望进一步提高频率稳定性。     

Ramsey-CPT原子频标的高性能小型脉冲微波源研究

根据Ramsey-CPT原子频标对脉冲微波源高性能小型化的要求,采用直接数字频率合成器（DDS）激励锁相环频率合成器,再结合可编程数字功率衰减器和阻抗匹配电路,从而实现具有高稳定度、高分辨率、快跳频速度、低相位噪声、小体积、小步长扫描的脉冲微波源。比较应用于Ramsey-CPT原子频标的脉冲微波源方案,介绍脉冲微波源的基本原理,简述其具体实现方法,并通过仿真优化得到最佳的输出性能。实现的脉冲微波源具有优良的技术性能,进一步提高了Ramsey-CPT原子频标输出频率的性能。同时,达到了设计小型化的要求,有利于Ramsey-CPT原子频标的便携式应用。     

New digital compensation technique for the design of amicrocomputer compensated crystal oscillator

The study of the stability of frequency sources is a matter of major interest due to the evolution of communication and instrumentation systems resulting in increasing the number of channels in a limited spectrum, and reducing size and power consumption. The paper relates laboratory experiences that explain the behavior versus temperature of thickness-mode quartz crystal resonators (AT- and SC-cut crystals) that are applied to the control of frequency sources, and the performance of digital compensation techniques. Prototypes of microcomputer-compensated crystal oscillators (MCXO's) have been developed to compare the compensation performance using the resonator as the temperature sensor against the use of an external sensor and verify the reduction of compensation errors due to thermal lags and hysteresis. The design of a CMOS integrated circuit for the MCXO is also included. A frequency correction method that does not modify the crystal resonance has been implemented in the circuit. This allows sensing of the temperature by means of the crystal and improving its long-term stability (aging). A new frequency comparator is also introduced. Its aim is to obtain the difference between two very close frequencies at its output, without being affected by the phase variations that the new frequency correction method and the digital circuit introduce. This detector has been implemented to get a high-resolution thermometric frequency and to realize a frequency-locked loop that includes a crystal controlled local oscillator, allowing the use of the MCXO as a good short-term stability source     

CPT铷原子钟锁相环频率合成器设计和分析

基于CPT(相干布局囚禁)87铷原子钟设计出输出频率为3417 MHz的锁相环频率合成器,通过ADIsimPLL仿真出最佳环路带宽,环路滤波器参数以及相位噪声等,并通过STM32对锁相环芯片进行控制。对频率合成器进行了测试,电路尺寸为40 mm×40 mm,输出信号功率范围为-4 dBm^+5 dBm可调,输出信号噪声满足要求-88.65 dBc/Hz@1 kHz,-92.31 dBc/Hz@10 kHz,-104.63 dBc/Hz@100 kHz,杂散和谐波得到抑制,设计的频率合成器能很好的应用于原子钟的射频信号源。     

A fractional-N frequency divider for multi-standard wireless transceiver fabricated in 0.18 μm CMOS process

With the rapid evolution of wireless communication technology,integrating various communication modes in a mobile terminal has become the popular trend.Because of this,multi-standard wireless technology is one of the hot spots in current research.This paper presents a wideband fractional-N frequency divider of the multi-standard wireless transceiver for many applications.High-speed divider-by-2 with traditional sourcecoupled-logic is designed for very wide band usage.Phase switching technique and a chain of divider-by-2/3 are applied to the programmable frequency divider with 0.5 step.The phase noise of the whole frequency synthesizer will be decreased by the narrower step of programmable frequency divider.△-Σ modulator is achieved by an improved MASH 1-1-1 structure.This structure has excellent performance in many ways,such as noise,spur and input dynamic range.Fabricated in TSMC 0.18 μm CMOS process,the fractional-N frequency divider occupies a chip area of 1130 × 510μm2 and it can correctly divide within the frequency range of 0.8-9 GHz.With 1.8 V supply voltage,its division ratio ranges from 62.5 to 254 and the total current consumption is 29 mA.     

SERF原子磁强计用半导体激光器驱动系统

在无自旋交换弛豫(Spin-Exchange Relaxation-Free,SERF)原子磁强计中,半导体激光器被用于极化碱金属原子和检测原子极化率,激光器出射光稳定与否直接关系到SERF原子磁强计的灵敏度,为了保证半导体激光器稳定工作,需要高性能的电流和温度控制单元。通过对激光器控制原理进行研究,以温度控制模块MTD415T和电流控制模块MLD203CHB为核心,通过"集成芯片+外部保护/降噪电路+上位机"的方式构建了一套半导体激光器驱动系统,实现了半导体激光器高稳定性的温度和电流控制,温度稳定性优于±5.0 m K,电流稳定性优于±2.1μA,同时相比较商用的控制器,体积大幅度缩小,促进了SERF原子磁强计的小型集成化。     

GPS驯服CPT原子钟方法研究

本文针对全球定位系统（GPS,Global Position System）接收机输出秒脉冲（1PPS,1 Pulse Per Second）信号的特点,以及相干布居囚禁（CPT,Coherent Population Trapping）原子钟输出频率信号的特性,设计并实现了GPS驯服CPT原子钟方案.我们建立了适合抑制1PPS信号抖动的卡尔曼滤波模型,通过理论推导和计算获得了相应噪声参数,并采用卡尔曼滤波器与平均滤波器相结合,对CPT原子钟输出频率实施滤波处理,并用GPS接收机输出的1PPS信号实施频率校准,所实现GPS驯服的CPT原子钟输出频率的中短期频率误差降低半个量级,天频率稳定度提高一个量级.     

A monolithic capacitive pressure sensor with pulse-period output

A new microminiature monolithic capacitive pressure transducer (CPT I) is 20 times more sensitive than piezoresistive strain-gauge pressure transducers, requires one percent of the power, and can be batch fabricated through current integrated circuit technology. A second device (CPT II) incorporates bipolar signal-processing electronics on the same silicon chip to produce a low-duty-cycle pulse-mode output with period related to pressure. This output format helps to re-solve the problem of shunting between leads, which is one of the principal causes of long-term drift in piezoresistive transducers designed for implantable medical applications. Because this device uses capacitance change as a transductional mechanism rather than piezo-resistivity, it is not susceptible to drift caused by temperature variations in the piezoresistive coefficient. Optimization for totally implantable biomedical applications places special emphasis on small size, high sensitivity, improved long-term baseline stability, and greatly reduced power consumption. These properties are also important for a wide range of pressure-sensing applications-from automotive to general industrial use.