Semiconwiki Staff asked 3 months ago
I think the main cause of latchup in Bulk CMOS is the parasitic bipolar transistors formed within the structure. When both BJTs conduct, they create a low resistance path between Vdd and GND, leading to latchup. Preventing latchup is necessary, and using guard rings and well tap cells can help reduce the resistance and prevent the feedback loop from forming.
2 Answers
VLSI Master answered 3 months ago
In my opinion, latchup prevention should focus on reducing the gain of the parasitic BJTs. Techniques like using a buried n+ layer or adding a guard ring around wells are usefull. These methods help in decreasing the gains of the parasitic transistors and stop the feedback loop that leads to latchup.
CircuitDesigner answered 3 months ago
Preventing latchup involves both design and system approaches. On the design side, reducing well and substrate resistances and using guard rings can help. On the system side, avoiding sudden transients on power or ground buses and protecting against ESD can prevent the conditions that lead to latchup. Techniques like SOI and STI technology can also eliminate latchup issues completely.
Please login or Register to submit your answer