Yuav ua li cas txo cov suab nrov ntawm photodetectors

Yuav ua li cas txo cov suab nrov ntawm photodetectors

Lub suab nrov ntawm photodetectors feem ntau suav nrog: suab nrov tam sim no, suab nrov thermal, suab nrov nrov, 1 / f suab nrov thiab suab nrov wideband, thiab lwm yam. Lub sijhawm no, peb yuav ua kom paub meej ntxiv cov yam ntxwv suab nrov thiab kev faib tawm los pab txhua tus neeg kom nkag siab zoo txog qhov cuam tshuam ntawm ntau hom suab nrov ntawm cov zis tawm ntawm photodetectors. Tsuas yog los ntawm kev nkag siab txog cov suab nrov tuaj yeem peb txo qis thiab txhim kho lub suab nrov ntawm photodetectors, yog li optimizing lub teeb liab-rau- suab nrov piv ntawm qhov system.

Lub suab nrov nrov yog qhov hloov pauv tsis sib xws uas tshwm sim los ntawm qhov tsis sib xws ntawm tus nqi nqa khoom. Tshwj xeeb tshaj yog nyob rau hauv cov nyhuv photoelectric, thaum photons tawm tsam photosensitive Cheebtsam los tsim electrons, tiam ntawm cov electrons yog random thiab conforms rau Poisson tis. Cov yam ntxwv spectral ntawm kev txhaj tshuaj nrov nrov yog tiaj thiab ywj pheej ntawm qhov ntau zaus, thiab yog li nws tseem hu ua suab nrov dawb. Kev piav qhia lej: Lub hauv paus txhais tau tias square (RMS) tus nqi ntawm kev txhaj tshuaj nrov tuaj yeem qhia tau tias:

Ntawm lawv:

e: Cov nqi hluav taws xob (kwv yees li 1.6 × 10-19 coulombs)

Idark: Tsaus tam sim no

Δf: Bandwidth

Cov suab nrov nrov yog proportional rau qhov loj ntawm qhov tam sim no thiab ruaj khov ntawm txhua zaus. Hauv cov mis, Idark sawv cev rau qhov tsaus ntuj tam sim no ntawm photodiode. Ntawd yog, thaum tsis muaj lub teeb, lub photodiode tsis xav tau lub suab nrov tam sim no. Raws li lub suab nrov ntawm qhov kawg ntawm lub photodetector, qhov loj dua qhov tsaus ntuj tam sim no, lub suab nrov ntawm photodetector ntau dua. Tsaus tam sim no tseem cuam tshuam los ntawm kev ua haujlwm tsis zoo ntawm lub photodiode, uas yog, qhov loj dua qhov kev ua haujlwm tsis zoo, qhov ntau dua qhov tsaus ntuj tam sim no. Txawm li cas los xij, qhov kev tsis ncaj ncees ua hauj lwm voltage kuj cuam tshuam rau kev sib txuas ntawm lub tshuab hluav taws xob photodetector, yog li cuam tshuam qhov ceev thiab bandwidth ntawm photodetector. Tsis tas li ntawd, qhov ntau dua qhov kev tsis sib haum xeeb, qhov ceev thiab bandwidth ntau dua. Yog li ntawd, nyob rau hauv cov nqe lus ntawm lub suab nrov, tsaus nti tam sim no thiab bandwidth kev ua tau zoo ntawm photodiodes, tsim nyog tsim yuav tsum tau nqa tawm raws li qhov tiag tiag project yuav tsum tau.

2. 1/f Flicker Noise

1/f suab nrov, tseem hu ua suab nrov flicker, feem ntau tshwm sim nyob rau hauv qhov tsawg-frequency range thiab muaj feem xyuam rau yam xws li cov khoom tsis xws luag los yog deg huv si. Los ntawm nws cov cim tej yam ntxwv zoo nkauj, nws tuaj yeem pom tau tias nws cov zog hluav taws xob ntau dua li qhov ntau zaus ua cov suab nrov, cov suab nrov ntau yam tsawg los ntawm 10 zaug. Lub zog spectral ceev ntawm 1 / f suab yog inversely proportional rau zaus, uas yog:

Ntawm lawv:

SI(f): Noise power spectral density

I: Tam sim no

f: zaus

1/f suab nrov yog qhov tseem ceeb nyob rau hauv qhov tsawg-frequency range thiab tsis muaj zog li qhov zaus nce. Cov yam ntxwv no ua rau nws yog qhov tseem ceeb ntawm kev cuam tshuam hauv kev siv tsawg zaus. 1 / f suab nrov thiab lub suab nrov dav dav feem ntau yog los ntawm lub suab nrov ntawm lub tshuab ua haujlwm hauv lub photodetector. Muaj ntau lwm qhov chaw ntawm lub suab nrov uas cuam tshuam rau lub suab nrov ntawm photodetectors, xws li lub hwj chim mov suab nrov ntawm kev ua haujlwm amplifiers, lub suab nrov tam sim no, thiab lub suab nrov thermal ntawm lub network tiv thaiv hauv qhov nce ntawm kev ua haujlwm amplifier circuits.

3. Voltage thiab tam sim no suab nrov ntawm lub lag luam amplifier: Qhov voltage thiab tam sim no spectral ntom yog qhia nyob rau hauv daim duab hauv qab no:

Hauv kev ua haujlwm amplifier circuits, lub suab nrov tam sim no tau muab faib ua cov suab nrov hauv theem tam sim no thiab cov suab nrov nrov tam sim no. Lub suab nrov hauv theem tam sim no i + ntws los ntawm qhov chaw sab hauv tsis kam Rs, tsim qhov sib npaug voltage suab nrov u1 = i + * Rs. I- Inverting tam sim no suab nrov ntws los ntawm qhov nce sib npaug resistor R los tsim qhov sib npaug voltage suab nrov u2 = I-* R. Yog li thaum RS ntawm lub hwj chim mov loj, lub suab nrov hloov los ntawm cov suab nrov tam sim no kuj loj heev. Yog li ntawd, txhawm rau txhim kho lub suab nrov zoo dua, lub suab nrov ntawm lub zog hluav taws xob (nrog rau kev ua haujlwm sab hauv) kuj yog ib qho tseem ceeb rau kev ua kom zoo dua qub. Lub spectral ceev ntawm lub suab nrov tam sim no tsis hloov nrog zaus variations ib yam. Yog li ntawd, tom qab tau amplified los ntawm Circuit Court, nws, zoo li qhov tsaus ntuj tam sim no ntawm lub photodiode, comprehensively tsim lub suab nrov ntawm lub photodetector.

4. Lub suab nrov thermal ntawm lub network tsis kam rau qhov nce (qhov ua kom muaj zog) ntawm kev ua haujlwm amplifier Circuit Court tuaj yeem suav nrog cov qauv hauv qab no:

Ntawm lawv:

k: Boltzmann tas li (1.38 × 10-23J/K)

T: Qhov kub thiab txias (K)

R: Resistance (ohms) thermal suab muaj feem xyuam rau qhov kub thiab txias, thiab nws cov spectrum yog tiaj tus. Nws tuaj yeem pom los ntawm cov qauv uas qhov loj dua qhov nce kev tiv thaiv tus nqi, qhov ntau dua lub suab nrov thermal. Qhov loj dua qhov bandwidth, lub suab nrov thermal yuav ntau dua. Yog li ntawd, txhawm rau xyuas kom meej tias tus nqi tiv thaiv thiab tus nqi bandwidth ua tau raws li qhov yuav tsum tau nce thiab qhov yuav tsum tau muaj bandwidth, thiab thaum kawg tseem xav tau cov suab nrov qis lossis siab teeb liab-rau-suab nrov piv, kev xaiv ntawm qhov nce resistors yuav tsum tau ua tib zoo txiav txim siab thiab ntsuas raws li qhov xav tau ntawm qhov project kom ua tiav qhov zoo tshaj plaws teeb liab-rau- suab nrov piv ntawm lub system.

Cov ntsiab lus

Kev txhim kho suab nrov thev naus laus zis ua lub luag haujlwm tseem ceeb hauv kev txhim kho kev ua haujlwm ntawm photodetectors thiab cov khoom siv hluav taws xob. High precision txhais tau tias tsis muaj suab nrov. Raws li thev naus laus zis xav tau ntau dua qhov tseeb, qhov yuav tsum tau muaj suab nrov, teeb liab-rau-suab nrov piv, thiab sib npaug lub suab nrov ntawm photodetectors kuj tau nce siab dua.