CHARGE TRANSFER DEVICE DIFFERENCING CIRCUIT

摘要

CHARGE TRANSFER DEVICE DIFFERENCING CIRCUIT A circuit is disclosed for obtaining an output signal proportional to the difference between two charge packet quantities nondestructively. The preferred embodiment includes a substrate with a potential well disposed under a floating gate electrode having charge transfer means for entering and removing charge from the potential well. A first quantity of charge Qa which is stored in the potential well is transferred out of the well at time t1 with a resulting proportional increase in the floating gate voltage which results from capacitor coupling from the charge to the floating gate. At a subsequent time t2 a second charge quantity Qb is transferred into the potential well and causes a proportional decrease in the floating gate voltage. The net change .DELTA.V in the floating gate voltage that results is proportional to the difference between the two charge quantities Q ant Qb.