Overview on Latch-Up Prevention in CMOS Integrated Circuits by Circuit Solutions

Abstract

In CMOS chips, the wider layout rules were traditionally applied to overcome latch-up issues. However, the chip area with wider layout rules was often enlarged, and in turn the chip cost was also increased. To effectively improve latch-up immunity without enlarging the chip area, circuit methods were therefore invented. An overview on circuit methodology used to prevent latch-up issues in CMOS integrated circuits (ICs) is presented in this article. The circuit solutions, including reducing the I/O pad trigger current, sensing the trigger current to control the power supply, and restarting the power supply through an MOS switch to shut off the latch-up current, are overviewed.

Keywords

• Latch-up
• latch-up prevention
• silicon-controlled rectifier (SCR)
• guard ring
• active guard ring
• voltage regulator