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????????????????????y????Ч??????(JFET)????????????????????????г?????仯????????????????????????????????????????????????????????????????????????????????????????????
????MEMS?????????????缼????????????????в????????????????,????MEMS?????????????????????????????????辧?????????γ?硢???????????????????????????????硣
??????????????????????????????ε???÷??棬MEMS????п?????????????????MEMS???罫???????25%??????????????2013????11????????????????????ζ?????????????о??г?????????????????????
??????????????????????????????????????????ECM???????????о?????????????????MEMS???????緽??????????????????
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????????????????????????????????MEMS???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????á?
??????????????????????????????????????????????????????????????????????????????Σ???????????????????????
?????????????94dBSPL???C26dBFS????????(SNR)?60-62dBc(A).
????PGA+ADC???????6.3??VRMS??????PGA?????3.2??VRMS.
?????????????94dBSPL???C26dBFS?????г?????(THD)<0.04%.
????????????г?????(THD)??????￡???????????????:710mVP-P.
????????????????ж?-42??-38dBV/Pa??????????12??14??16dB???.
????о???????????450??A.
???????????????????????????????????в???????????豸????У????????????????(SPL:soundpressurelevel)????????????????????????С?????Lp????20??????(??Pascal)??????????????????С??????????
????????1???????С??Ч???????????????????94dBSPL.
??????Lp(1Pascal)=20log10(1Pa/20??Pa)=93.97dB(SPL)??94dB(SPL).
???????????????????ECM????????????-42??-38dBV/Pa?????????????????????????1???????????????-42??-38dBV????????????????????????dBV?????1Vrms(??Ч????????????????)???????????????????????????????С??????,-42dBV=7.9mVRMS=22.4mVP-P?????,120dBSPL ??????????????????????120dBSPL?C94dBPa/SPL?C42dBV/Pa=-16dBV????????158.5mVRMS,????????????????????????dBFS,??νdBFS????ADC?????????ADC?ο????????????????20??log10(VIN??AV/VREF)=dBFS?????????????????(FractionalFullScale),???????????????????????120dBSPL????????Av(?????????)??VREF???VIN??AV/VREF=1???????ЩAv??VREF???????????о??????????????????????????????о???0dBFS???120dBSPL,-26dBFS?????94dBSPL???
????????????????????????????????????????dBc????dB???????c???????(carrier),?????????????????????????????????????????dBc,??????????????????94dBSPL???C26dBFS?????????62dBc(A)????????120dBSPL??0dBFS?????????88dBc(A)??32dBSPL???C88dBFS????????(SNR)?0dBc????Ч???????????????????????????????(NoiseFloor)=32dB(SPL),??????????=32dBSPL?C94dBPA/SPL?C42dBV/Pa=-104dBV=6.3??VRMS??????????????????о??????????Χ?32-120dB(SPL)??
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