"Latchup Triggering Mechanisms"

Pamela Obiomon
Prairie View A&M University


This paper provides guard ring solutions for different types of latchup triggering mechanisms.  It is not possible to provide detailed design rules valid for all designs and all technologies.  However, it is possible to provide guard ring structure design guidelines which will minimize latchup for particular environments or triggering modes.   There are only two types of guard rings used to minimize latchup, minority and majority carrier rings.  However, there are numerous ways to layout the guard structure providing many solutions for latchup minimization.  The choice is a matter of circuit geometry and application.  To create a design with high latchup immunity, information about the most likely triggering mechanism should be known and the technology of the circuit.  For example if a circuit is fabricated using the P-well CMOS technology and the circuit will be used in an environment in which it will be exposed to ionizing radiation, the guard ring structure which will minimize latchup most  is a double majority carrier guard ring.  This paper describes many latchup triggering mechanism and provides guard ring solutions.

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