Improve latch-up immunity by circuit solution

A concept of active guard ring and its corresponding circuit solution to enhance the latch-up immunity of integrated circuits (IC) are proposed and verified in a 0.6-um 5-V CMOS process. By detecting the over-shooting/under-shooting trigger current during latchup current test (I-test), some compensation current generated from on-chip ESD PMOS or NMOS devices through special circuit design can effectively reduce the latchup trigger current that injecting into the core circuit blocks. Therefore, the latchup immunity of I-test with positive or negative trigger current applied at the I/O pins can be significantly improved.