MODELING THE POSITIVE-FEEDBACK REGENERATIVE PROCESS OF CMOS LATCHUP BY A POSITIVE TRANSIENT POLE METHOD .1. THEORETICAL DERIVATION

Abstract

A novel method to characterize the mechanism of positive-feedback regeneration in a p-n-p-n structure during CMOS latchup transition is developed, It is based on the derived time-varying transient poles in large-signal base-emitter voltages of the lumped equivalent circuit of a p-n-p-n structure, Through calculating the time-varying transient poles during CMOS latchup transition, it is found that there exists a transient pole to change from negative to positive and then this pole changes to negative again, A p-n-p-n structure, which has a stronger positive-Feedback regeneration during turn-on transition, will lead to a larger positive transient pole, The time when the positive transient pole occurs during CMOS latchup transition is the time when the positive-feedback regeneration starts, By this positive transient pole, the positive-feedback regenerative process of CMOS latchup can he quantitatively characterized.