恒温温补石英晶体振荡器

提出了一种恒温温补晶振(OCTCXO)的实现方法,该OCTCXO由两部分组成:温度补偿晶体振荡器(TCXO)和恒温槽。TCXO放置在恒温槽中,恒温槽是一个负反馈自动控制系统,当环境温度小于恒温槽设定的温度时,OCTCXO相当于一个恒温晶体振荡器(OCXO);当环境温度大于恒温槽设定的温度时,恒温槽停止工作,整个OCTCXO的频率-温度稳定性由TCXO决定,由于OCTCXO最高工作温度与恒温槽设定的温度之间的温度区间很小,使得TCXO在该温度区间内的频率-温度稳定性得到较大的改善,从而提高OCTCXO的频率-温度稳定性。实验结果表明,该OCTCXO标称频率10 MHz,在-40～70℃温度范围内频率-温度稳定性为±1×10-7;最大功耗为1.15 W,常温工作时功耗为410 mW;体积为21.0 mm×13.0 mm×5.1 mm。     

加速度对晶体振荡器频率稳定度的影响

晶体振荡器作为电子系统中频率控制的标准信号源，是整个系统有序运行的关键。由于电子产品都在向微型化发展，工作的环境条件对晶体振荡器的影响更加严峻，尤其在空间技术和地面移动系统中，加速度对晶体振荡器频率稳定度的影响已经成为一个重要的研究方向。本文就加速度影响晶体振荡器频率稳定度的机理，加速度敏感度的测量试验方法，以及降低加速度敏感度的措施等作了论述。     

宽温高稳定度的温度补偿技术

通过对常用两种温度补偿方式的比较,介绍了一种改进型双Г电阻补偿网络作为宽温补偿技术。改进型双Г电阻补偿网络集成了桥式电阻网络和双Г电阻网络的优点,在高低温极值处具有更强的补偿能力。试验表明,采用该种补偿网络的温补晶振在-55℃~ 85℃的宽温范围内,频率温度稳定度优于±1×10-6。     

高稳定度晶体振荡器降低相位噪声的设计实践

本文简要介绍了高稳晶振的相位噪声，着重讨论了如何从电路上实现为低相位噪声高稳定度晶体振荡器的设计，并给出了实验结果，作了相应讨论。     

高稳定度晶体振荡器降低相位噪声的设计实践

简要介绍了高隐晶振的相位噪声，着得讨论了如何从电路上实现对低相位噪声高稳定度晶体振荡器设计，并给出了实验结果，作了相应讨论。     

一种带高阶温度补偿的片内时钟振荡器设计

本文基于0.18μm CMOS工艺,设计了一款适用于片上系统SoC的无需晶振的片内12MHz时钟信号产生电路。利用高阶温度补偿方案,该时钟振荡器能在较宽的温度范围内实现振荡频率的高稳定性。此外,电路的稳压器设计使得振荡器频率在电源电压变化时也能保持相当好的稳定性。仿真结果表明,在-40℃~125℃温度范围内,此振荡器振荡频率的温度系数仅为40ppm/℃,电源电压变化±10%时,振荡频率的相对误差仅为±0.012%,完全能够满足常规数字系统的要求。     

一种用于RFID标签带温度补偿的振荡器设计

提出了基于TSMC 0.18μm RF CMOS工艺带温度补偿高精度振荡器的设计方案。针对射频电子标签应用的设计要求,选用改进型的双电容张弛振荡器结构。通过温度补偿作用,参考电压与输出电流受电源影响较小,保证了振荡器输出频率的稳定性。使用SPECTRE工具对电路进行仿真,在1.8 V电源电压下,-25¹00℃范围内,中心频率为1.92 MHz时最大偏差小于±0.75%,达到使用的要求,并在此基础上完成电路的版图。     

低温晶体失效故障分析

在计算机的实验中,晶体在温度试验条件下,性能不稳定,导致计算机无法正常工作。通过对晶体的失效分析,确定了晶体失效的原因。结果表明：由于晶体谐振器内部晶片的形成结构异常造成晶体谐振器与振荡电路不能相互匹配,因而在低温条件下表现出来,这种晶体谐振器内部晶片结构异常是导致计算机无法正常工作的原因。通过对晶体谐振器进行温度频差测试,发现晶体谐振器早期失效问题,可解决这一问题,验证试验表明这一措施有效、可行。     

基于晶振频率补偿的高精度数字时钟设计

为解决普通晶振频率长期漂移量较大的问题,提出了一种用GPS秒脉冲对晶振脉冲在线自动测量及修正,从而产生本地高精度时钟的方法,据此设计了一种基于单片机和CPLD的智能自校准数字时钟系统。介绍了时钟产生及校准模块、鉴相及相差测量模块等硬件电路组成和数据采集、晶振误差补偿算法实现等软件设计。该系统在需要较高精度时间显示的场所具有实际应用价值。     

Process and temperature compensation in a 7-MHz CMOS clock oscillator

This paper reports on the design and characterization of a process, temperature and supply compensation technique for a 7-MHz clock oscillator in a 0.25-/spl mu/m, two-poly five-metal (2P5M) CMOS process. Measurements made across a temperature range of -40/spl deg/C to 125/spl deg/C and 94 samples collected over four fabrication runs indicate a worst case combined variation of /spl plusmn/2.6% (with process, temperature and supply). No trimming was performed on any of these samples. The oscillation frequencies of 95% of the samples were found to fall within /spl plusmn/0.5% of the mean frequency and the standard deviation was 9.3 kHz. The variation of frequency with power supply was /spl plusmn/0.31% for a supply voltage range of 2.4-2.75 V. The clock generator is based on a three-stage differential ring oscillator. The variation of the frequency of the oscillator with temperature and process has been discussed and an adaptive biasing scheme incorporating a unique combination of a process corner sensing scheme and a temperature compensating network is developed. The biasing circuit changes the control voltage of the differential ring oscillator to maintain a constant frequency. A comparator included at the output stage ensures rail-to-rail swing. The oscillator is intended to serve as a start-up clock for micro-controller applications.     

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     

MAS9270模拟温补晶振芯片原理及应用

MAS9270仅需附加一只晶体谐振器就能够构成一只压控、温补晶体振荡器(VCTCXO),主要介绍MAS9270的内部结构及补偿原理,给出了利用Microchip公司MPLABICD开发工具完成晶体振荡器补偿、编程、校验工作,实现能够完全满足MAS9270技术指标要求的压控温补晶体振荡器的设计方法.     

电容式触摸屏输入技术在便携应用中前景广阔

本文比较了电阻式、“外表面”电容式、“内表面”电容式触摸屏的原理及特点,指出“内表面”电容式触摸屏机械结构更简单。透光率更高．生产成本更有优势,在便携应用中前景广阔。[编者按]     

TD-TTL crystal oscillator

The crystal oscillator constructed on the basis of Deng's (1979) RC oscillator with a tunnel diode and a TTL inverter has excellent characteristics, such as : high speed, wide band of working frequencies, sine and pulse waveforms at the output. The consideration of the oscillations condition and the measured characteristics of the circuit are given.