| 摘要 |
PURPOSE:To enable set-off compensation of stray capacity, by connecting the semiconductor capacitor wherein an insulating layer is embedded between two semiconductor layers to the inversed input terminal of an operational amplifier. CONSTITUTION:A semiconductor layer N<+>1 is opposed to a conductor layer 11 through an insulating layer S1 on a P type silicon substrate 4 and the terminal ends of the opposed layers form an overlapped part L1 while a semiconductor layer N<+>2 is opposed to the conductor layer 11 through an insulating layer S2 and the terminal ends of the opposed layers form an overlapped part L2. In this case, the layers N<+>1, N<+>2 are held under an electrical continuity state and, further, in the space between opposed leading end edge parts of the overlapped layers N<+>1, N<+>2, a thick insulating layer 10 is embedded between the substrate 4 and the layer 11 to electrically block both layers N<+>1, N<+>2. Therefore, even if any drive signal is supplied to the layer 11, the formation of a channel is not formed on the substrate 4 and, therefore, the stray capacity thereof is uniquely determined as the sum of capacities C2', C2''. As a result, electrostatic capacity for compensating a semiconductor capacitor is always held to a definite value to gate voltage showing alternating change between power source voltage and earth and, therefore, the set-off compensation of stray capacity at the reversal input terminal of an operation amplifier becomes good.
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