ESD protection circuitry with multi-finger SCRS

Abstract

Self-triggered Multi-finger SCRs used in ESD protection circuitry capable of turning on all SCR fingers of the multi-finger SCRs include a first source, a second source, N SCR units, (N−1) diodes, and N resistors. Each of the N SCR units includes a first node, a second node coupled to the second source, and a trigger node. An nth diode of the (N−1) diodes is coupled between a first node of an nth SCR unit and a trigger node of an (n+1)th SCR unit. An nth resistor is coupled between the first node of the nth SCR unit and the first source, wherein n and N are integers. The (N−1) diodes can be replaced by directly coupled the first node of the nth SCR unit to the trigger node of the (n+1)th SCR unit when a trigger pulse is applied at the trigger node of a first SCR unit.