Patent 7576962 was granted and assigned to Bourns, Inc. on August, 2009 by the United States Patent and Trademark Office.
A method and apparatus for transient blocking relying on a transient blocking device and a sampling circuit. The transient blocking device has at least one depletion mode n-channel device interconnected with at least one depletion mode p-channel device such that a transient alters a bias voltage Vp of the depletion mode p-channel device and a bias voltage Vn of the depletion mode n-channel device in such a manner that the depletion mode devices mutually switch off to block the transient. The sampling circuit is interconnected with the depletion mode p-channel device and the depletion mode n-channel device to determine whether the transient persists. In the event of a persistent transient, the sampling circuit uses a disconnect element for permanently blocking the transient blocking device. Various types of voltage pinching and disconnect elements, including depletion mode devices of the n-channel and p-channel type can be employed in the sampling circuit to sample the transient and permanently block the transient blocking device.