高性能SAW振荡器的频率稳定性

近几年来,高稳定性SAW振荡器的研制已取得了重大的进展,能对密封的SAW谐振器精确地进行频率调整,SAW振荡器的频率稳定性也有了显著的改进。500MHz SAW谐振振荡器的相位噪声达到了-184dBc/Hz,同时在10Hz的载波偏置条件下,闪变效应噪声为-83dBc/Hz。在±150kHz调谐范围内,验证了400MHz SAW延迟线振荡器样机的相位噪声为-170dBc/Hz,在10Hz的偏置条件下,其闪变效应噪声电平为-70dBc/Hz。检测到SAW器件的振动灵敏度为10~(-10)/g量级,最近还对采用混合电路的900MHz SAW谐振振荡器进行了同样的振荡灵敏性检测。按规定制作的500MHz SAW谐振振荡器的长期频率稳定性高达±1ppm/a。     

以非线性理论阐述反馈振荡器的频率与幅度的稳定性

本文首先对线性的频率稳定理论用于近似正弦反馈振荡器的线性频率稳定理论,进行了评论性的回顾。在这方面,解释所谓的线性振荡器是清楚的。其后,是应用描述函数法和判决方程法所得到新的表达式,去阐述反馈振荡器考虑成一个非线性网络时的振荡频率和振荡幅度的稳定性。     

基于可编程控制器多谐振荡器的设计与分析

在数字电路中,常常需要一种不需外加触发脉冲就能够产生具有一定频率和幅度的矩形波电路,特别是要求频率和占空比可调的这种电路,它就是多谐振荡器.文章采用可编程控制器来设计完成该功能,它具有设计简单,完成方便,频率和占空比用软件就可调试,不需要对电路重新组装的特点.     

微多晶硅梁开关振荡器

本文提出了一种新型的多晶硅梁微静电开关结构,并在考虑硅梁固定边张力的情况下对多晶硅梁的受力弯曲、静电吸合等情形进行了有效的静力学理论分析。 利用微静电开关的充电吸合、放电弹开这一电、机过程,本文还实现了一种成本极低的微硅梁静电驱动振荡器。初步研究结果表明,硅梁的振动频宽大约为2.1kHz,振动幅度较小,振动平衡点在下电极附近。     

2．4GHz电压控制振荡器的设计与仿真

通过分析测量BJT的S参数与稳定因子定,并利用已测量的BJT输出阻抗ZOUT来设计输出匹配电路,使整体电路在2．4GHz的频率上产生振荡。利用ADS软件对电路进行仿真。达到在BJT特定的偏压下。仍在2．4GHz的频率上持续振荡。并可利用电压的变化来控制其振荡频率的目的。     

一种温度不敏感占空比可调的振荡器

介绍了一种单比较器型锯齿波及CLK方波震荡器电路,它通过基准电压源对RT/CT充放电产生一定占空比的锯齿波及CLK方波信号。该电路所产生的方波及锯齿波频率的温度和电压稳定性好,波形的占空比可根据需求进行trimming调节。同时介绍了电路的工作原理,进行了HSPICE仿真,最后给出了流片验证结果。     

寄生不灵敏的开关电容三相振荡器

本文提出并讨论了两种使用开关电容技术设计振荡器的新方法。设计出的振荡器产生三相对称正弦信号,在通信、信号处理等领域有广泛应用。本文使用了两类RC振荡器作为模拟振荡器原型:一类是SD振荡器,另一类是三状态变量振荡器。由此实现的SC振荡器均易于集成,其振荡频率与时钟频率的关系是线性的,并具有电路特性对寄生电容不灵敏,电容比较小的显著特点。文中给出了比较结果和实验结果。实验结果与理论值相符。     

宽负载应用的自适应关断时间Boost电路

设计了一种新型自适应关断时间(AFT)模式Boost电路。不同于传统的采样输入/输出电压的自适应电路,该AFT模式Boost电路直接采用真实的占空比信息,设置了自适应比较点,解决了开关频率受负载电流影响的问题。基于0.5 μm CMOS工艺对电路进行仿真验证。结果表明,当输入电压在2.4~4.2 V、负载电流在0.3~1.2 A范围内变化时,该AFT模式Boost电路的工作频率稳定在967~972 kHz之间,频率变化范围仅为传统自适应电路的14.3%。     

高性能数控振荡器的设计

设计了一个低抖动、高分辨率的DCO(数控振荡器)。该DCO由7级单端倒相器构成,通过分析输出时钟抖动、分辨率与每级倒相器尺寸之间的关系,找到设计的最佳尺寸,最终实现版图。采用0.35μm1P4M CMOS工艺,3.3 V电源供电,振荡频率为280 MHz~550 MHz,分辨率为10 ps。Hspicerf仿真结果表明,DCO输出时钟为385 MHz时,峰-峰值抖动为70.35 ps。     

Fundamentals of oscillator performance

The oscillator is arguably the most essential part of any communication system: it defines a channel frequency, or timing and synchronisation in a digital system. The phase noise of any oscillator has a fundamental lower limit. It limits the achievable efficiency of spectrum use and degrades the error rate in practical applications. Any low-noise oscillator can be described as a positive-feedback Q-multiplier circuit. Such a model shows that phase noise is minimised if the square of the effective circuit Q and the signal-to-noise ratio in the oscillator are maximised. This simple fact is true for all oscillators and it provides the basis for more efficient and lower noise designs     

混沌振荡器的计算机仿真

提出了用频变负电阻(FDNR)实现混沌振荡器的新电路,该电路结构简单,易于集成,仅用一个接地的频变负电阻作为有源器件,用二极管提供必要的非线性。并给出了电路的数学模拟和PSpice仿真。模拟和仿真结果表明,二者取得了很好的一致。     

具有CRT式快速运动图像响应时间的高性能液晶显示器

为了研究显示器中的运动图像模糊问题,我们推导出了一个简单的方程,将运动图像响应时间与液晶或者有机发光二极管的响应时间以及帧率结合起来。从方程中可以看出,减小运动图像响应时间有3种方法：（1）减小液晶响应时间|（2）提高帧率|（3）选取合适的背光开关占空比。在显示器帧率为120 Hz时,如果液晶的响应时间小于2 ms,那么液晶显示器的运动图像响应时间与有机发光二极管显示器相当。液晶的响应时间可以通过两种方法提高：（1）采用超低黏性系数的液晶材料|（2）开发快速响应液晶显示器工作模式。同时,为了使液晶显示器达到像阴极射线显像管一样快速的运动图像响应时间（< 1.5 ms）,我们可以增加帧率或者减小背光开关占空比。     

High repetition rate LC oscillator

LC oscillators have been built which can produce multikilowatt RF pulses in the megahertz frequency range with repetition rates of tens of kilohertz. The L and C for these oscillators can be determined from the frequency requirement and the high-Q requirements. The high repetition rates are achieved using a high-pressure spark-gap switch together with a dc to ac inverter power supply. Closely spaced antenna elements can be used to increase the number of cycles in the radiated waveforms (radiated Q).     

High frequency Wien-type chaotic oscillator

A Wien-type oscillator based on a current feedback opamp (CFOA) employed as a non-inverting voltage-controlled voltage source is modified for chaos by adding an inductor and a general purpose signal diode. By using a CFOA as the active element, high operating frequencies are possible. The chaotic oscillator is described by a fourth order system of differential equations. Experimental results, PSpice simulations and numerical simulation of the proposed model are included     

快启动振荡器(FOX)提升了超外差性能

大多数汽车中常见的遥控无钥匙门禁(RKE)系统,是简单RF数据传输的一个常见应用。RKE系统可控制车门的开关,旅行箱的开合,防盗报警。将来的应用还可能包括远距离汽车的定位和启动。RKE系统由类似钥匙扣的发射器(通常每人一个)和车上的接收器构成。该系统的工作频率一般在300～450MHz之间,但在欧洲有些新系统正考虑使用ISM频段分配的868MHz。RKE系统的通讯是单向的,数据只从发射器到接收器。这种通信方式不但成本低,而且可以延长发射器里电池的寿命。RKE系统的工作很直观。开始工作时,用户按下钥匙扣上的按钮,启动内部的单片机发出…     

High quality LTCC resonator for voltage-controlled oscillator

Design and technology of microwave conductor lines embedded in low-temperature cofired ceramic (LTCC) multilayer substrates are summarized with a focus on achieving the highest possible quality (Q) factor for a given line inductance. The work was initiated to test the integrability of base station voltage-controlled oscillators (VCOs) in ceramic multilayer substrates. This approach leads to a miniaturization of current versions by a factor of 2 to 4. However, base station specifications for phase noise and hence resonator Q are extremely demanding. Therefore, both the design and the processing technology were optimized. By choosing a twin-line design with two parallel lines vertically separated by a single LTCC layer, Q factors of 90 and 180 have been achieved for integrated 5.5 nH inductors at frequencies of 640 MHz and 1650 MHz, respectively. Application of this result to VCO modules in standard LTCC technology already yields low phase noise levels, e.g., -136 dBc/Hz at 100 kHz offset, which is suitable for base station applications. However, further noise reduction is expected from a dedicated high Q fabrication process that uses conventional via punching and filling steps to replace the ceramic material between the two lines by conductive silver paste. This raises the Q to 120 and 200, respectively, at the two frequencies and adds extra degrees of freedom to LTCC design for low-loss wireless solutions.     

Monte Carlo simulation of a millimeter-wave Gunn-effect relaxation oscillator

A large-signal computer simulation of a GaAs millimeter-wave Gunn-effect relaxation oscillator has been developed. This computer simulation utilizes a Monte Carlo computation of the electron distribution behavior rather than relying on an analytical expression for the velocity-field characteristic now known to be inaccurate at millimeter-wave frequencies. Results of this simulation are presented for a 70-GHz fundamental oscillator. The device simulated is consistent with currently produced millimeter-wave designs with an active length of 2.0 µm and doping density of 1 × 10¹⁶cm³. A peak efficiency of 2.4 percent with an output power of 144 mW was determined. The device can be characterized as operating in an accumulation transit mode, but with the proverbial "dead-zone" at the cathode.     

基于Multisim的西勒振荡器设计与仿真

针对解决西勒振荡器传统讲授理论性较强,缺乏直观性,教学效果不理想的目的,采用了引入电路仿真软件Multisim进行设计、分析的方法 ,通过电路频率特性、反馈特性、负载特性、频率稳定度试验仿真,得出振荡频率为404.978 k Hz、峰峰值为8.00 V的西勒振荡器电路设计满足要求,仿真结果与理论分析基本一致。虚拟软件与传统讲授结合,加深了学生对高频电子线路理解和记忆,提高了学习效率。     

FEL oscillator performance optimization with astigmaticebeams

A model is presented for an FEL amplifier with an astigmatic electron beam propagating through a linearly polarized, linearly tapered wiggler. The model is used to examine FEL resonator performance as a function ofe-beam focusing in the wiggle plane perpendicular to the plane of polarization of the magnets.