Patent ID: 8929047
Filing Date: 2015-01-06
Classification: H04M

Abstract:
1. A protection circuit for protecting at least one solid state circuit at a line interface, the protection circuit comprising: at least one first transistor; at least one first bias supply for supplying a first bias current to said at least one first transistor; wherein the supplied first bias current is at least a current required to operate said first transistor; said first transistor and said first bias supply comprise a first protection circuit providing protection of a first polarity; at least one second transistor; at least one second bias supply for supplying a second bias current to said at least one second transistor, wherein the supplied bias current is greater than or equal to a bias current required to operate said second transistor; said second transistor and said second bias supply comprise a second protection circuit providing protection of a second polarity opposite to said first polarity; and at least one further transistor, wherein a gate of said at least one further transistor is derived from between the first said transistor and ground.