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该文对横向电场激励下的(yxl)-58°LiNbO_3压电谐振器的高频振动进行了研究。首先,基于Mindlin一阶板理论,计算了压电谐振器的模态频谱关系,得到晶体基板长厚比;然后,利用有限元分析软件COMSOL Multiphysics建立了谐振器的三维有限元模型,通过增加厚度方向网格扫掠层数的方法,验证了仿真模型的网格无关性;其次,通过特征频率计算与频域计算得到了谐振器一阶厚度剪切模态频率值;最后,通过改变电极与晶体板质量比以及电极间距的大小,获得了不同尺寸参数对谐振器高频振动特性的影响规律。仿真分析结果表明,电极与晶体板的质量比同谐振器谐振频率成负相关,质量比越大,谐振频率越小;电极间距值与谐振频率成负相关,间距值越大,谐振频率越小。 相似文献
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石英谐振器可以作为传感器的敏感元件。为了减小温度等因素的干扰,提高石英晶体谐振器力敏特性,通过能陷理论及其厚度剪切石英晶体谐振能量分布曲线的计算,在同一圆形晶片上设计了多电极力敏谐振器集群。根据共模抑制原理,将谐振器集群输出频率信号作差频处理,以此抑制温度等因素的干扰,再将差频信号叠加以提高石英晶体谐振器集群整体力敏特性。实验结果表明,石英谐振器集群差频输出的温频特性明显优于传统的单电极谐振器,石英晶体谐振器集群整体力灵敏度系数提高到9 992 Hz/N。 相似文献
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设计了一种新型的单基三电极石英晶体谐振器,并在大气环境条件下测试分析了这种谐振器的频率-度特性,验证了其频率-度特性与已有的单基单电极谐振器的频率-温度特性基本一致,曲线为三次曲线.在相同激励及环境条件下,在同一基片上设置多对电极时,各对电极构成的谐振器的频率-温度特性基本相同.根据这种相似特点,将同一基片上不同电极对应的谐振器的振动频率进行差频补偿,可有效地抑制温度对谐振器振动频率的影响.这种谐振器所采用的差频补偿方法可为石英谐振器相关特性的进一步开发利用提供依据.研究了这种结构的石英晶体谐振器的晶片表面处理(是否抛光)及边沿形状(是否倒边)对其频率-温度特性的影响.实验结果表明,对单基多电极石英晶体谐振器的晶片表面进行抛光并对边沿进行倒边处理后,谐振器的稳定性得到了有效的改善,性能得到了优化. 相似文献
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设计了一种新型的单基三电极石英晶体谐振器,并在大气环境条件下测试分析了这种谐振器的频率-温度特性,验证了其频率-温度特性与已有的单基单电极谐振器的频率-温度特性基本一致,曲线为三次曲线。在相同激励及环境条件下,在同一基片上设置多对电极时,各对电极构成的谐振器的频率-温度特性基本相同。根据这种相似特点,将同一基片上不同电极对应的谐振器的振动频率进行差频补偿,可有效地抑制温度对谐振器振动频率的影响。这种谐振器所采用的差频补偿方法可为石英谐振器相关特性的进一步开发利用提供依据。研究了这种结构的石英晶体谐振器的晶片表面处理(是否抛光)及边沿形状(是否倒边)对其频率-温度特性的影响。实验结果表明,对单基多电极石英晶体谐振器的晶片表面进行抛光并对边沿进行倒边处理后,谐振器的稳定性得到了有效的改善,性能得到了优化。 相似文献
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设计了一种新型的单基三电极石英晶体谐振器,并在大气环境条件下测试分析了这种谐振器的频率-温度特性,验证了其频率-温度特性与已有的单基单电极谐振器的频率-温度特性基本一致,曲线为三次曲线。在相同激励及环境条件下,在同一基片上设置多对电极时,各对电极构成的谐振器的频率-温度特性基本相同。根据这种相似特点,将同一基片上不同电极对应的谐振器的振动频率进行差频补偿,可有效地抑制温度对谐振器振动频率的影响。这种谐振器所采用的差频补偿方法可为石英谐振器相关特性的进一步开发利用提供依据。研究了这种结构的石英晶体谐振器的晶片表面处理(是否抛光)及边沿形状(是否倒边)对其频率-温度特性的影响。实验结果表明,对单基多电极石英晶体谐振器的晶片表面进行抛光并对边沿进行倒边处理后,谐振器的稳定性得到了有效的改善,性能得到了优化。 相似文献
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利用ANSYS有限元理论模型分析AT切石英晶体受沿x轴方向的对径力作用时晶片内的应力分布情况,并计算三电极位置处的应力变化比值。测试了三电极谐振器的基频振荡频率,并计算其相应的力频系数。通过比较ANSYS仿真分析的结果和实验所得结果,表明ANSYS仿真分析计算结果与实验结果基本一致,从而证明ANSYS仿真分析是可行的。因此,在同一晶体基片上设计谐振器时,可借助有限元分析手段,根据晶片内的应力分布情况,在有限空间范围内初步选择应力变化差异较大的位置设置电极,以此获得力频敏感特性显著的集成式石英晶体谐振器。 相似文献
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在研究石英晶体谐振器力敏特性与加力方位角关系及晶体薄片内波的传播特性的基础上,设计制作了基于同一晶体基片上的集成式四电极谐振器.研究了这种结构的谐振器的力敏特性与加力方位、谐振频率稳定性与基片表面和边沿结构的关系.实验结果表明,谐振器的力敏特性与加力方位密切相关;对晶体基片表面进行抛光处理,能有效地消除表面缺陷对谐振器振动状态的影响,提高谐振频率的稳定性;对晶体基片边沿进行倒边处理,能缩短谐振波波幅在边沿区衰减的空间距离,抑制了谐振器振动能量沿晶片边沿的散失,使谐振器频率稳定性得到进一步提高.经表面抛光及边沿倒边处理后,谐振器频率波动的平均值分别下降到处理前的42%和30%. 相似文献
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设计了一种可用于射频(RF)通信系统中的MEM平行板可变电容,采用新颖的双间隔(two-gap)结构、金属铝极板、折叠“Y”形支撑和厚度不均的可动极板。用CoventorWare软件模拟了电容的C-V特性,当控制电压从0变化到10V时,RF信号电容相应从0.37pF增加到5.64pF,变容比约为15.24∶1;用HFSS软件模拟了电容的S11参数,电容的品质因数Q在1.8GHz下约为77.78。 相似文献
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《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1969,57(10):1723-1734
Trapped energy resonators and transducers have attained a considerable importance in quartz crystal technology both as single-frequency resonators for the control of crystal oscillators and as drivers for the monolithic crystal filter which appears likely to have a wide use as a channel filter for the separation of voice frequency channels for long-distance carrier systems, microwave radio, and submarine cable systems. It is the purpose of this paper to derive the equations for trapped energy resonators of the thickness-shear and thickness-twist types and to calculate the ratios of capacitances for straight crested waves. It turns out that the ratios are lower (coupling higher) than are observed in practice. It appears that this difference is connected with the finite width of the plate which causes the motion at the edge of the plate to be somewhat smaller than the motion in the center of the plate. While no exact solution has been obtained for the finite plate, an approximation is made which is in good agreement with the experiment. The resonator on a plate is a symmetrical device, whereas a transducer for driving a monolithic filter is a dissymmetrical device since it is driving different impedances on its two boundaries. To represent this dissymmetry requires a distributed network representation which is somewhat similar to that found for a plane longitudinal or shear wave except that the propagation constant for a trapped wave replaces that of the plane wave. The representation also requires a transformer whose transformation ratio is a function of the frequency and two negative element terms. By transformations the negative elements can be made to disappear. These together produce an equivalent circuit whose values depend on the ratio of the electrode length to the crystal thickness. 相似文献
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掺CeO2纳米MnO2非对称超级电容器的研究 总被引:2,自引:0,他引:2
采用化学共沉淀法制备出超级电容器用掺CeO2的MnO2电极材料,通过XRD、SEM对样品进行了表征,研究了掺杂量对MnO2电极稳定性能的影响。结果表明,产物主相为α-MnO2,粒度分布较均匀,在50~100nm;在6mol/L的KOH电解液中,该掺杂MnO2电极材料具有优良的电容行为和循环稳定性能。当掺CeO2量为10%(与MnO2的质量比)时,在电流密度为250mA/g时,比电容量达257.68F/g;循环500次,容量仅衰减1.18%。 相似文献
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The deleterious effects of crystal shunt capacitance and series resistance on the performance of series-mode oscillators are discussed. When the parasitic capacitance across the crystal significantly modifies the transconductance of the amplifying stage the circuits can become susceptible to a parasitic second mode of oscillation above the series-resonance frequency of the crystal. A simple model that can sufficiently describe such crystal oscillator circuits was developed and used to derive simple design equations that can accurately predict the behavior of these circuits. The design equations should be especially useful for a reliable design in cases when it is not practical to use an additional inductor to compensate for the parasitic shunt capacitance of the crystal. It is shown theoretically that the inclusion of this capacitance in the feedback path reduces the total effective capacitance in the tank circuit, which is tuned to the desired overtone frequency. This creates a second mode of oscillation frequency which is higher than the desired crystal resonance frequency. The ranges of loop-gain and tank resistance values that can prevent this parasitic mode of oscillations are derived. It is also shown that the useful loop gain for the desired oscillations to start is restricted to a similar region by the crystal shunt capacitance and series resistance 相似文献
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Mirtaheri P Grimnes S Martinsen OG 《IEEE transactions on bio-medical engineering》2005,52(12):2093-2099
In this paper, we characterize the polarization impedance behavior of several common metals in diluted NaCl solution operated at low current densities. The objective was to provide a useful reference for those wishing to calculate the electrode polarization impedance in diluted NaCl solutions. Serial equivalent resistance (R) and capacitance (C) for silver, aluminum, gold, platinum, and medical stainless-steel were measured as a function of frequency (10(-2)-10(3) Hz) and NaCl concentration (2.4-77.0 mmol/L). The ratio of electrode polarization impedance with respect to the bulk resistance was calculated and plotted against concentration for each metal. Such a ratio shows the effect of the electrode polarization contribution as a function of electrolyte concentration when the bulk resistance of the solution changes. All metals showed a decrease of serial resistance Rp and capacitance Cp as a function of frequency. The medical stainless-steel electrode showed largest impedance values at lower frequencies compared to the other electrodes, and was concentration independent at all frequencies. Aluminum had smallest polarization impedance at low frequencies. Pure gold and platinum behaved similar with the exception that the serial resistance for gold showed a lower value at higher frequencies. 相似文献
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《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1976,64(8):1249-1250
A new technique is developed for the precise determination of the equivalent circuit parmeters of a quartz crystal resonator: the series resonance frequency, the series resistance, the series inductance, and the capacitance ratio. This technique is unique in that the parameters are determined from the measured data of the crystal admittance by means of computer processing. 相似文献