Protection circuit that can be associated with a filter

A structure for protection against electric surges, connected between two input terminals and two output terminals, the two output terminals being adapted for connection to inputs of a circuit to be protected, wherein:

• a first input terminal of the two input terminals is connected to a first output terminal of the two output terminals via an impedance,
• a second input terminal of the two input terminals is connected to a second output terminal of the two output terminals;
• the first input terminal is interconnected to the second input terminal across a first avalanche diode;
• the first output terminal is interconnected to the second output terminal across a second avalanche diode of a same polarity as the first avalanche diode;
• and
• wherein the impedance is a tripole impedance, a third terminal of which is connected to the second input terminal and the second output terminal, elements of the tripole impedance forming, with the first and second avalanche diodes, a filtering structure;
• and
• wherein the tripole impedance includes two series resistors and a parallel capacitor.