Abstract Virtually complete charge transfer can be achieved with charge coupleddevices(CCDs)intheburiedchannelconfigurationbecausetheburiedchannelCCDintroduces no transfer noise. However, conventional charge detectors incorporatedinto CCDs have a comparably large noise, which consists of thermal noise and 1/fnoisefromMOS transistorin theoutputchargedetectors.
10Low-NoiseElectronicImagingwithDouble-GateFETs
235Fig.10.20Detector
structure
Fig.10.21Potentialdiagramsofsensingchannel.(a)Saturationconditioninopenloop.(b)Compressedconditionbynegativefeedback.(c)Saturationconditioninnegativefeedback
coef cientandthefeedbackampli ergain,respectively.Inthisdetector,kisequaltoCg=.CgCCc/,whereCgandCcarethegatecapacitanceofthedetectiontransistorandthediffusioncapacitanceofthen-typesensingchannelundertheFPP,respectively.ItisderivedfromthepartitionratiooftheCgandCcseriescapacitances.
NoiselesssignalchargeisconvertedintothevoltagesignalS,whilethedetectornoiseisNintheopen-loopchargedetector.Byapplyingtheinvertedoutputsignalontothefeedbackgate,notonlythevoltagesignalbutalsothedetectionnoiseiscompressed,andtheyresultinS0andN0.Signal-to-noiseratioS0=N0isequalto
