H型亚微米梁的混频特性测量

本文简述了H型亚微米梁的工艺实现过程,从实验上详细研究H型梁的两种混频方式:向下混频和向上混频.考察的H型梁长度分别为8μm、10μm、12μm和15μm,小激励下谐振频率分别为13.30 MHz、8.77 MHz、6.12 MHz和3.65 MHz.通过在梁上施加两路不同频率的静电激励信号,调整两信号频率差值及和值在梁的本振频率附近变化,经过梁的自适应过程实现信号混频,最后由多普勒测振仪检测梁的混频特性.实验结果表明梁在向下混频时的振幅随两路信号频率的平移而改变,出现所谓的窗口效应;对于这两种混频方式,混频分量越接近梁的本征频率,梁的振幅越大,反之梁振幅下降越多;在输入信号功率均设置为14 dBm时,对比向上混频,向下混频使得梁的振幅更大,诸如12μm长的梁向下混频时梁振幅为4.082 nm,而向上混频时混频处振幅仅为1.826 nm.

Measurement of Frequency Mixing Characteristics of H-Type Submicron Beams

The fabrication process of H-type submicron beam actuated by electrostatic force was presented briefly and its two mixing methods,down-mixing and up-mixing,were studied experimentally in detail.Four sets of H-type beams with the length of 8 μm,10 μm,12 μm and 15 μm were examined,whose small signal resonant frequencies were 13.30 MHz,8.77 MHz,6.12 MHz and 3.65 MHz,respectively.Two separate frequency signals were applied to beams,and then the offset or the summation of these two frequencies was set to be close to the resonant frequency of the beam to achieve frequency mixing which was detected by a Doppler vibrometer eventually.Experimental results indicate that in down-mixing,the vibration amplitude of the beam depends on the frequency band in which the frequencies of two signals change synchronously,which is called window effect.The vibration amplitude of the beam will be the maximum at the beam resonant frequency for both down-mixing and up-mixing.Compared with up-mixing,the H-type beam can get greater vibration amplitude when it is working on down-mixing mode.When two equal input powers were set to be 14 dBm,the 12 μm long beam can get the vibration amplitude of 4.082 nm when it is working on down-mixing mode,while only 1.826 nm in amplitude when it is working on up-mixing.