共查询到19条相似文献,搜索用时 125 毫秒
1.
2.
我台的激励器,在常温和冬季能达到要求,夏季因气温上升,刚校频后差拍周期大于180秒;不到一小时频率漂移稳定度变差,严重时会出现校不到频的情况。用电风扇散热,频率稳定度有一定改善。II501高稳压控晶体振荡器,采用的是内、外双层恒温结构形式。此压控要求额定工作温度在0~45℃,常温时,激励器内压控周围温度比机 相似文献
3.
高精度的恒温结构是设计高稳恒温晶体振荡器的关键,为了获取高稳定的恒温晶振,根据以往的经验,我们设计了3种恒温槽结构,并运用ANSYS Icepak软件对这3种结构进行热仿真,通过仿真结果比较得出最优方案,最终设计出体积为36mm×27mm×13mm的恒温晶体振荡器,其频率温度稳定度≤1x10-9,实践证明,Icepak软件进行恒温晶体振荡器的设计,以优化恒温槽的结构?提高工作效率。 相似文献
4.
一、概述频率稳定度是振荡器(包括压控振荡器)的一个非常重要的指标。在用途日益广泛的窄带锁相环中,对压控振荡器的频率稳定度提出更为苛刻的要求。因此,人们对压控振荡器频率稳定度的研究及测量越来越关心和重视。一提起频率稳定度,就会马上想到既有联系又有区别的长期频率稳定度和短期频率稳定度这两个概念。本文只对决定压控振荡器(VCO)短期频率稳定度的内部噪声功率谱密度进行分析和测量,并换算成秒频率稳定度。测量VCO噪声功率谱密度的方法很多,在文献中有详细论述。我们这里不是把 相似文献
5.
本文在介绍压控晶振主要技术指标的基础上阐述了5MHz精密压控晶振的组成及晶振电路、恒温控制电路的工作原理,介绍了提高其性能的措施,最后给出了实测结果。 相似文献
6.
为了提高CMOS环形振荡器的稳定度,以温度传感器作为检测电路,利用单稳态电路整形、滤波,把频率变化转变为电压变化对压控振荡器(VCO)进行负反馈调节,在温度变化和电源微小波动时,抑制了频率漂移.测试结果表明:CMOS环形振荡器输出频率为3.55 GHz,在温度区间-20~80℃内最差稳定度为2.45%,优于2.5%,达... 相似文献
7.
接收机的相位噪声实际上专指频率合成器的相位噪声,而频率合成器的相位噪声是衡量其短期稳定度的一个技术指标,目前国内外的频率合成器基本采用锁相环(PLL)或多个锁相环的方式.频率合成器的频率稳定度包括长期稳定度和短期稳定度.长期稳定度一般由基准频率源(通常为恒温晶振或温度补偿晶振,或由外部基准频率源)决定,短期频率稳定度由锁相环决定(环路参数、部件如压控振荡器).相位噪声早期也称为相位抖动,在时域多用阿仑方差表示,在频域多用相位噪声(偏离载波某个频偏处的单位带宽内相位噪声功率相对主载波的功率低多少,通常用dBc/Hz表示,dBc中的c表示相对值)表示. 相似文献
8.
一种可获得高稳定度的温控电路沈才忠(浙江省计量测试技木研究所,杭州.310013)恒温干燥箱、生化培养箱、恒温液体班等试验设备是化学分析、检测工作中必不可少的。对于各种试验设备,就其性能而言,箱(槽)体内的温度稳定度是一个重要的技术指标。影响温度稳定... 相似文献
9.
10.
介绍了38.88MHz压控石英晶体振荡器的原理、设计和性能。该振荡器由适当频率温度曲线的谐振率,变容二极管移相器,高性能的放大电路,波形转换电路等组成,振荡器具有高的稳定度,良好的调谐范围和占空比。 相似文献
11.
12.
简要介绍了一种小型的恒温晶体振荡器,通过对振荡参数的反复试验、修改,提高了振荡器的频率稳定度。提出一种新的设计理念,利用晶体谐振器与电感随温度变化对晶体振荡器频率所产生的不同影响,合理安排晶体振荡器内部的热场,调整晶体谐振器、热敏电阻及振荡参数的热平衡关系,在去掉恒温槽的情况下提高了温度频率特性,且大大缩小了晶体振荡器的体积。 相似文献
13.
《Electron Devices, IEEE Transactions on》1967,14(9):522-525
The output power of a cavity-controlled Gunn oscillator has been measured at a frequency of 10 GHz, as a function of bias voltage over the temperature range 30°C to 120°C. The measurements were made using 500-ns pulses to avoid significant changes in-device temperature during a pulse, and at a duty cycle of 20:1 to maintain a low mean input power. The device was operated in a coaxial cavity made of invar, and temperature control effected by operating the cavity in an oven. It has been found that ranges of bias voltages exist over which power output and efficiency is extremely sensitive to temperature changes, and that, depending on the particular conditions, power output can either increase or decrease. The effect of increasing temperature has also been found to reduce the bias voltage required to obtain maximum power output and efficiency. 相似文献
14.
15.
介绍一种简单而有效的提高集成电路稳定性的电路补偿方法.当电路制造过程中的工艺参数、工作电压或工作温度发生变化时,根据仿真结果,该方法可以使MOS晶体管跨导的标准差比未经补偿的电路降低41.4%.这种电路可以用于CMOS LC振荡器中. 相似文献
16.
17.
18.
《Solid-State Circuits, IEEE Journal of》1978,13(6):799-805
A single-stage differential amplifier, implemented in a standard metal-gate process, serves as a basis for consideration of specific characteristics of analog CMOS circuits. The dependence of important circuit parameters like open-loop gain and gain-bandwidth product on transistor geometries, and biasing current are derived. Furthermore, it is shown how to improve the amplifier characteristics by optimizing the layout. The differential amplifier stage is compared with an equivalent one based on a standard bipolar process. This comparison shows that the CMOS stage exceeds in the low-current region (nanoamperes) not only the possible voltage gain but also the gain-bandwidth product of a bipolar stage. The results are applied to the design of a multichannel telemetry transmitter for patient monitoring. The transmitter chip incorporates a digital part for the multiplex control and a precise analog part for the modulation unit. The modulator is a voltage controlled oscillator and consists of two parts: a voltage-to-current converter and a current controlled oscillator. The linear range of the voltage-to-current converter is limited to at most three decades due to the offset of MOS transistors. The current controlled oscillator, however, has a linear range of more than seven decades. This was made possible by applying a new design principle, which is specific for CMOS technology. Besides the large linear range the multivibrator has excellent temperature stability. The chip area is 4 mm/SUP 2/. 相似文献
19.
An integrated CMOS micromechanical resonator high-Q oscillator 总被引:2,自引:0,他引:2
A completely monolithic high-Q oscillator, fabricated via a combined CMOS plus surface micromachining technology, is described, for which the oscillation frequency is controlled by a polysilicon micromechanical resonator with the intent of achieving high stability. The operation and performance of micromechanical resonators are modeled, with emphasis on circuit and noise modeling of multiport resonators. A series resonant oscillator design is discussed that utilizes a unique, gain-controllable transresistance sustaining amplifier. We show that in the absence of an automatic level control loop, the closed-loop, steady-state oscillation amplitude of this oscillator depends strongly upon the dc-bias voltage applied to the capacitively driven and sensed μresonator. Although the high-Q of the micromechanical resonator does contribute to improved oscillator stability, its limited power-handling ability outweighs the Q benefits and prevents this oscillator from achieving the high short-term stability normally expected of high-Q oscillators 相似文献