Owner manual

6
TH7899M
2201A–IMAGE–02/02
OutputAmplifiers TheTH7899Msensorhasfouroutputamplifiers.Thesearelocatedineachcornerof
thedeviceattheendsofthereadoutregister.Chargepacketsareclockedtoapre-
chargecapacitor(floatingdiffusion)whosepotentialvarieslinearlywiththequantityof
chargeineachpacket.Thispotentialisappliedtotheinputgateofatwostagesource
followeramplifierandtheoutputsignalisread.Then,theresetclockΦRremovesthe
chargefromthefloatingdiffusionviatheresetdrainVDRwhichimposesitsreference
level.
Figure5.On-chipOutputAmplifierStructure
Multi-Pinned-Phase
(MPP)Mode
TheTH7899MsensoroperatesintheMPPmodeinordertosubstantiallydecreasedark
current(typicallyfrom0.6nA/cm
2
to25pA/cm
2
at25°C).Comparedtostandardtechnol-
ogy,theMPPmodeallows,whilekeepingallotherperformancesunchanged,eitherto
increaseexposuretime,ortooperateathighertemperature.
DarkcurrentisduetothermalgenerationinthesubstrateoftheCCD.Thedifferentgen-
erationsourcesareasfollows:
• surfacestatesattheSi-SiO
2
interfacewhichisthemaincontribution
• generationanddiffusioninthebulk
• generationinthedepletedzone
Ifthegatesarebiasedwithadequatenegativebiases,holesappearattheSi-SiO
2
inter-
faceandfillintheinterfacestatessuppressingtheirdarkcurrentcontribution.Asa
result,onlytheminorbulkanddepletedzonecontributionsremain.
AbsoluteMaximumRatings*
Storagetemperature..................................... -55°Cto+150°C
Operatingtemperature ................................... -40°Cto+85°C
Temperaturecycling ...................................................15°C/mn
*NOTICE: StressesabovethoselistedunderABSOLUTE
MAXIMUMRATINGSmaycausepermanent
devicefailure.Functionallyatorabovetheselim-
itsisnotimplied.Exposuretoabsolutemaximum
ratingsforextendedperiodsmayaffectreliability.