Automatic methodology for placing the guard rings into chip layout to prevent latchup in CMOS IC's

Abstract

A program methodology is proposed to automatically place the guard rings in the chip layout to improve latchup immunity of the CMOS IC's. The additional guard rings between the I/O cells and the internal circuits had been practically proven to significantly increase the latchup immunity of CMOS IC's. Therefore, the layout spacing from the I/O cells to the internal circuits can be reduced to a reasonable distance to save the total chip size. In this paper, a "Guard Ring Automation" program to realize the additional guard rings in the layout is proposed to make the layout more automatically and accurately.