Multifinger-type electrostatic discharge protection element

摘要

A multifinger ESD protection element has between an input wiring to which a surge current is input and a reference-potential wiring, 2n-number (where n is a natural number of 2 or greater) of fingers F₁ to F_2n. A drain resistor Rd_i (i=1 to 2n), NMOS transistor T_i and source resistor Rs_i are connected serially in each finger F_i in the order mentioned. A single unit U_j is constructed by two mutually adjacent fingers F_2j-1 and F_2j (where j is a natural number of 1 to n). In each unit the source of one transistor is connected to the gate of the other transistor and the source of this other transistor is connected to the gate of the first-mentioned transistor. The source S_2j of finger F_2j is connected to the source S_2j+1 of the next unit U_n+1. The 2n-number of fingers are connected in the form of a ring.