Test: Latch-up In CMOS - Electrical Engineering (EE) MCQ

In latch-up condition, parasitic component gives rise to low resistance conducting path between Vdd and Vss with disastrous results. Carefull control during fabrication is necessary to avoid this problem.

Latch-up can be induced by glitches on the supply rail or by incident radiation.

Two transistors and two resistances might bring up the latch-up effect in p-well structure. These are associated with p-well and with regions of the substrate.

An increase in substrate doping level with a consequent drop in the value of Rs can be used as a remedy for latch-up problem.

The introduction of guard rings can reduce the effect of latch-up problem. Guard rings are diffusions which decouple the parasitic bipolar transistors.

BiCMOS process produces circuits which are less likely to suffer from latch-up problems where as CMOS circuits are very highly prone to latch-up problems.

One of the main factor in reducing the latch-up effect is reduced n-well resistance Rw. Reduction in Rw means that a larger lateral current is necessary to invite latch-up and higher value of holding current is also required.

 The parasitic pnp transistor has the effect of reducing carrier lifetime in the n-base region.

The parasitic pnp transistor has the effect of reducing carrier lifetime in the n-base region which results in radiation in beta.

Latch-up is the generation of low-impedance path in CMOS chips between the power suppply and ground rails.