ACTIVE GUARD RING STRUCTURE TO IMPROVE LATCH-UP IMMUNITY

Abstract

An active guard ring structure is provided, which is applicable to improving latch-up immunity during the latch-up current test (I-test). The proposed active guard ring structure comprises an I/O circuit and an active protection circuit, wherein the I/O circuit receives a trigger current via an input pad and generates a corresponding bulk current since being triggered. The active protection circuit, connected between the I/O circuit and a core circuit, detects whether the trigger current is a positive or negative current pulse. When an intensity of the trigger current is larger than a threshold value, the active protection circuit controls the I/O circuit to provide a sink or compensation current so as to neutralize the bulk current and to reduce the net current flowing into or sourced from the core circuit, thereby increasing the latch-up resistance and immunity of the core circuit.