Patent ID: 8089302

Claim:
An apparatus, comprising: a first transistor element with at least three terminals, wherein a first terminal is supplied with a first voltage, and a second terminal is supplied with a second voltage; a first switching unit, wherein a third terminal of the first transistor element is connected to a ground potential via the first switching unit; and a second transistor element, formed as an N-MOS transistor, wherein a first terminal of the second transistor element is connectable to the third terminal of the first transistor element, and a second terminal of the second transistor element is connected to the ground potential, wherein the first transistor element has a predefined threshold voltage, the first voltage and the second voltage are predefined alternating voltages, and the first transistor element is configured such that in case a differential voltage between the first predefined alternating voltage and the second predefined alternating voltage is higher than the predefined threshold voltage and the first switching unit is not conductive, the third terminal is charged with the first predefined alternating voltage.