Theprincipleofthetwocarrierscontributingtocarrythepixelsignalchargesisfirstlypresented,andthenthebipolarjunctionphotogatetransistor(BJPT)withhighperformanceisproposedfortheCMOSimagesensor.Thenumericalanalyticalmodelofthephoto-chargetransferforthebipolarjunctionphotogateisestablishedindetail.Somenumericalsimulationsareobtainedunder0.6μmCMOSprocess,whichshowthatitsreadoutrateincreasesexponentiallywiththeincreaseofthephoto-chargeatappliedvoltage.