CHARGE DETECTING CIRCUIT

专利名称：CHARGE DETECTING CIRCUIT发明人：YAMADA TETSUO申请号：JP13879184申请日：19840704公开号：JPS6118174A公开日：19860127

摘要：PURPOSE:To realize a charge detecting circuit having a high sensitivity and asuperior linearity, by partially decreasing the density of P type or N type impurity fordecreasing the junction capacity in the electrostatic capacity of a P-N coupled chargedetecting layer. CONSTITUTION:A P<-> type layer 17 having the same type ofconductivity as a substrate 1 and a sufficiently low density of impurity is provided

adjacent to an N<+> type diffused layer 2. The region surrounded by broken lines 18 is adepletion layer. Since the P<-> type impurity layer 17 surrounding the diffusion layer 2has a low density, the thickness Xd of the depletion layer is increased. The junctioncapacity CFV is decreased and the total electrostatic capacity CFD is also decreased,whereby the sensitivity of detecting charge is improved. When it is assumed that the P<-> type impurity layer 17 has the density of impurity corresponding to 1/16 of that of thesubstrate 1, the capacity CFV is decreased to 1/4 if the density of N type impurity layer>> the density of the P type impurity layer. Further, the decrease in the non-linearjunction capacity improves the linearity of the charge detecting characteristics.

申请人：TOSHIBA KK

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