Momwe mungachepetse phokoso la photodetectors

Momwe mungachepetse phokoso la photodetectors

Phokoso la photodetectors makamaka zikuphatikizapo: phokoso panopa, matenthedwe phokoso, kuwombera phokoso, 1/f phokoso ndi wideband phokoso, etc. Nthawi ino, tifotokoza mwatsatanetsatane zamtundu waphokoso ndi magulu kuti tithandizire aliyense kumvetsetsa bwino momwe phokoso lamitundu yosiyanasiyana limakhudzira ma siginecha amtundu wa photodetector. Pokhapokha pomvetsetsa magwero a phokoso tingathe kuchepetsa bwino ndikuwongolera phokoso la photodetectors, potero kukulitsa chiŵerengero cha chizindikiro ndi phokoso la dongosolo.

Phokoso la kuwombera ndi kusinthasintha kwachisawawa komwe kumachitika chifukwa cha zonyamula katundu. Makamaka mu mphamvu ya photoelectric effect, pamene ma photons agunda zigawo za photosensitive kuti apange ma elekitironi, kupanga ma elekitironiwa kumachitika mwachisawawa ndipo kumagwirizana ndi kugawa kwa Poisson. Mawonekedwe owoneka bwino a phokoso lowombera ndi lathyathyathya komanso lopanda ma frequency magnitude, motero amatchedwanso phokoso loyera. Kufotokozera kwa masamu: Mtengo wapakati wapakati (RMS) wa phokoso lowombera ukhoza kufotokozedwa motere:

Mwa iwo:

e: Malipiro apakompyuta (pafupifupi 1.6 × 10-19 coulombs)

Idark: Mphamvu yakuda

Δf: Bandwidth

Phokoso la kuwombera limayenderana ndi kukula kwa pompopompo ndipo ndi lokhazikika pama frequency onse. Mu formula, Idark imayimira mdima wakuda wa photodiode. Ndiko kuti, popanda kuwala, photodiode ili ndi phokoso lakuda lakuda. Monga phokoso lachibadwa kumapeto kwenikweni kwa photodetector, kukula kwa mdima wamakono, phokoso la photodetector limakulirakulira. Mdima wakuda umakhudzidwanso ndi kukondera kwa voliyumu ya photodiode, ndiko kuti, kukulira kwa voliyumu yokondera, kumapangitsanso mdima wapano. Komabe, kukondera kumagwira ntchito voteji kumakhudzanso mphambano capacitance wa photodetector, potero kulimbikitsa liwiro ndi bandiwifi ya photodetector. Kuphatikiza apo, kuchuluka kwa voliyumu yakukondera, kumathamanga kwambiri komanso bandwidth. Choncho, ponena za phokoso lowombera, mdima wakuda ndi bandwidth ntchito ya photodiodes, mapangidwe oyenera ayenera kuchitidwa molingana ndi zofunikira zenizeni za polojekiti.

2. 1/f Flicker Phokoso

Phokoso la 1/f, lomwe limadziwikanso kuti phokoso la flicker, limachitika makamaka pama frequency otsika ndipo limagwirizana ndi zinthu monga kuwonongeka kwa zinthu kapena ukhondo wapamtunda. Kuchokera pazithunzi zake zowoneka bwino, zitha kuwoneka kuti mphamvu zake zowoneka bwino ndizocheperako pamagawo apamwamba kwambiri kuposa momwe zimakhalira pafupipafupi, ndipo pakuwonjezeka kwanthawi 100 zilizonse, phokoso la spectral density limachepetsa nthawi 10. Kuchuluka kwamphamvu kwamphamvu kwa 1/f phokoso kumayenderana ndi ma frequency, ndiko kuti:

Mwa iwo:

SI (f) : Phokoso lamphamvu yowoneka bwino

Ine: Panopa

f: pafupipafupi

Phokoso la 1/f ndilofunika kwambiri pamayendedwe otsika ndipo limafowoka pomwe ma frequency akuwonjezeka. Chikhalidwe ichi chimapangitsa kukhala gwero lalikulu la zosokoneza pamagwiritsidwe otsika kwambiri. Phokoso la 1/f ndi phokoso la wideband makamaka limachokera ku phokoso lamagetsi la amplifier yogwira ntchito mkati mwa photodetector. Palinso magwero ena ambiri a phokoso omwe amakhudza phokoso la ma photodetectors, monga phokoso lamagetsi la ma amplifiers ogwira ntchito, phokoso lamakono, ndi phokoso lotentha la network yotsutsa pakupeza mabwalo a amplifier.

3. Phokoso lamagetsi ndi laposachedwa la amplifier yogwira ntchito: Kuchulukana kwamagetsi ndi mawonekedwe amakono akuwonetsedwa pachithunzi chotsatirachi:

M'mabwalo ogwiritsira ntchito amplifier, phokoso lamakono limagawidwa mu-gawo phokoso lamakono komanso phokoso lamakono. Phokoso laposachedwa la i+ limayenda kudzera pa gwero lamkati la Rs, ndikupanga phokoso lofanana la voltage u1 = i+*Rs. I- Inverting phokoso lamakono limayenda kupyolera mu phindu lofanana ndi resistor R kuti apange phokoso lofanana la voteji u2 = I-* R. Choncho pamene RS ya mphamvu yamagetsi ndi yaikulu, phokoso lamagetsi lotembenuzidwa kuchokera ku phokoso lamakono limakhalanso lalikulu kwambiri. Chifukwa chake, kukhathamiritsa kwa phokoso labwino, phokoso lamagetsi (kuphatikiza kukana kwamkati) ndi njira yofunikira pakukhathamiritsa. Kachulukidwe kakachulukidwe ka phokoso lapano sikusinthanso ndi kusiyanasiyana kwafupipafupi. Chifukwa chake, itatha kukulitsidwa ndi dera, izo, monga mdima wamakono wa photodiode, zimapanga phokoso la kuwombera kwa photodetector.

4. Phokoso lotentha la network yokana kuti lipindule (amplification factor) ya dera lothandizira amplifier limatha kuwerengedwa pogwiritsa ntchito njira iyi:

Mwa iwo:

k: Boltzmann nthawi zonse (1.38 × 10-23J/K)

T: Kutentha Kwambiri (K)

R: Kukaniza (ohms) phokoso lotentha limakhudzana ndi kutentha ndi mtengo wokana, ndipo mawonekedwe ake ndi athyathyathya. Zitha kuwoneka kuchokera ku chilinganizo kuti kukula kwa mtengo wokana kukana, kumapangitsanso phokoso lalikulu. Kukula kwa bandwidth, phokoso lalikulu la kutentha lidzakhalanso. Chifukwa chake, kuwonetsetsa kuti mtengo wotsutsa ndi mtengo wa bandwidth umakwaniritsa zonse zomwe zikufunika kupindula ndi zofunikira za bandwidth, ndipo pamapeto pake zimafunanso phokoso lochepa kapena chiŵerengero chapamwamba cha phokoso la phokoso, kusankha kwa zopinga zopindula kuyenera kuganiziridwa mosamala ndikuwunikiridwa potengera zofunikira zenizeni za polojekiti kuti mukwaniritse chiŵerengero choyenera cha phokoso ndi phokoso la dongosolo.

Chidule

Ukadaulo wowongolera phokoso umachita gawo lalikulu pakupititsa patsogolo magwiridwe antchito a ma photodetectors ndi zida zamagetsi. Kulondola kwambiri kumatanthauza phokoso lochepa. Popeza ukadaulo umafunikira kulondola kwambiri, zofunikira za phokoso, chiŵerengero cha ma signal-to-phokoso, ndi mphamvu zofanana zaphokoso za ma photodetectors nawonso akuchulukirachulukira.