[小學(xué)教育]mems技術(shù)第六講噪聲與器件的性能(已修改)
2024-12-19 23:23 本頁面
【正文】 MEMS和微系統(tǒng)設(shè)計 課程的基本目的 ?掌握 MEMS設(shè)計的基本過程 ?掌握 mems機電及其耦合分析的基本理論 ?掌握機電結(jié)構(gòu)微器件的性能分析方法 ?了解熱、流體的基本理論 ?了解 MEMS的發(fā)展前沿知識 ?培養(yǎng)對 MEMS的興趣 課程內(nèi)容 ? MEMS概述及 MEMS設(shè)計的概述 ? 工藝簡要回顧 ? 系統(tǒng)設(shè)計、工藝設(shè)計及版圖設(shè)計 ? 主要的機械、電子元件及其設(shè)計基礎(chǔ) ? 多域耦合設(shè)計：以機電耦合為例子 ? 器件性能的估計 ? 簡單的其他域的元件及其簡要設(shè)計要點 ? 設(shè)計實例 本章提綱 ?噪聲處理的基本知識和類型 ?器件的分辨率 ?系統(tǒng)的分辨率 Noise ? Noise: Random fluctuation of a given parameter I(t) ? In addition, a noise waveform has a zero average value ? We can’t handle noise at instantaneous times ? But we can handle some of the averaged effects of random fluctuations by giving noise a power spectral density representation ? Thus, represent noise by its meansquare value: ? ? ? ?2L e t ( ) 0 , 0Di t I t Ii t w h il e i??????? ? 222 01Th e n i l im TDDTI I I I d tT??? ? ? ??Noise Spectral Density ? We can plot the spectral density of this meansquare value: Circuit Noise Calculations ? Deterministic: ? Random: ? ? ? ? ? ?0 ij H j j? ? ? ? ??? ? ? ? ? ? ? ? ? ? ? ?2*0 iiS H j H j S H j S? ? ? ? ? ???????? ? ? ? ? ?0 iS H j S? ? ??Handling Noise Deterministically ? Can do this for noise in a tiny bandwidth (., 1 Hz) ? ? ? ?2 1 1 1 1n nS f S f Bf? ?? ? ? ??? Can approximate this by a simusoidal voltage generator (especially for small B, say 1 Hz) [This is actually the principle by which oscillators work ? oscillators are just noise going through a tiny bandwidth filter] Why? Neither the amplitude nor the phase of a signal can change appreciably within a time period 1/B. Systematic Noise calculation procedure General Circuit with Several Noise Source ? Assume noise sources are uncorrelated 1. For replace w/a deterministic source of value 21ni? ?211z1Hnniif???Systematic Noise Calculation Procedure 2. Calculate (treating it like a deterministic signal) 3. Determine 4. Repeat for each noise source: 5. Add noise power (mean square values) Total RMS value ? ? ? ? ? ?11o n ni H j? ? ? ??? ? ? ? 22211o n ni H j? ? ???2 2 21 2 3,n n ni v v2 2 2 2 21 2 3 4o n TO T o n o n o n o nv v v v v? ? ? ? ? ? ? ?2 2 2 21 2 3 4o n T O T o n o n o n o nv v v v v? ? ? ? ? ? ? ?噪聲源 ?干擾噪聲（理論可消除：隔離和共地） ?機械噪聲（ thermal noise : brownian noise） ?電噪聲 thermal noise (johnson noise) shot noise (散粒噪聲） 1/f noise Mechanical (Brownian) Noise Impinging molecules give rise to a Brownian noise force: 2 4nBf k Tb f?? ? ?1 / d a m p in g c o e f f ic ie n tb M Q???Noise force applied to Mkb system results in random Brownian motion with a frequencydepenndent power spectrum: ? ?22221141/Bnk T b fxfffQf???????? ???? ??Implications: ff1 ? Electronic Noise Sources 1. Thermal noise in resistors generated by random motion of electrons or holes white spectral density (up to 10 THz) 2 4nBv k TR f?? spectral density Example: R=1kΩ, T=300 K 2 /4nBv f k TR??22/ 4 / 4n r m s nv f n V H z v v m V? ? ? ?Thermal Noise (cont.) Thermal
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