Patent ID: 9337822
Filing Date: 2016-05-10
CPC Classification: H01J,H03K

Claim Text:
1. A switch circuit that includes plural transistor elements connected in series in such a manner that the source of one element is connected to the drain of another between high voltage and a system ground and that switches a connection state between the high voltage and the system ground, the switch circuit comprising: a first transistor element the source of which is connected to the system ground among the plural transistor elements; a second transistor element the source of which is connected to the drain of the first transistor element in a shared manner and the drain of which is connected to the high voltage side among the plural transistor elements; a third transistor element the drain of which is connected to the gate of the second transistor element in a shared manner; and a resistor element that is connected in parallel between the gate and the source of the second transistor element, wherein: voltage enough to turn on the second transistor element is applied to the source of the third transistor element when the source of the second transistor element is the system ground; the first transistor element and the third transistor element are turned off to turn off the second transistor element, so that the high voltage is disconnected from the system ground; and the first transistor element and the third transistor element are turned on to turn on the second transistor element, so that the high voltage is connected to the system ground.