回复 1# 吴天创
cmos combination combine NMOS and PMOSstructure . In some cases the N and P structure use in each process can createa parasitic path between the supply and the ground. By using a guard ring thedesigner can reduce these parasitic effects (NPN-PNP parasitic transistors created).The parasitic effect in this case is called:latch up. The latch up is basically a SCR circuit. If it turns on, it runs fastto an increasing current due to positive feedback causing malfunctioning or evendestruction. Recommend you to read the book of ‘the art of analog layout’ |