| 摘要 |
PURPOSE:To improve a surge-proof performance by linking the material to concatenate and connect an FET for a surge-proof to an input terminal and connecting the section between the middle point of the concatenating contact of the FET for the surge-proof and a ground terminal with an FET for protection. CONSTITUTION:At the time of the element action, a voltage necessary to pinch off FFT 12 and 13 for surge-proof and an FET14 for protection is impressed to an external terminal 11. At this time, the cut-off FET 12 and 13 for the surge-proof play the role of the DC prevented capacitor and at the time of the element action, the surge noise voltage added to an input terminal 8 is divided and attenuated. A capacity value shown by connecting serially the FET 12 and 13 for the surge-proof to the gate of an FET 1 for driving comes to be 1/2 when the FET is single and the dividing effect of a surge noise voltage is increased. Further, since the FET 14 for protection is also cut-off-shaped, a signal to pass through the out-off capacity of the FET 12 and 13 for the surge-proof is not attenuated and impressed to the gate of an FET1 for driving. |
