Hi all,

When a differential input single ended opamp is used in a feeback , consider the case when it is used in bandgap voltage reference circuits, it forms
both positive and negative feeadback loop. Negative feedback loops are stable do not have worry about it much, but postive feebacks results in oscillations if
the gain is > 1 (Barkheusen criteria).  So in the above case, I mean in bandgap circuits,  we can just assure the total system to be stable by making the
loop gain of negative feedback > loop gain of positive feedback, my question is  this (just this one condition loop gain of negative feedback > loop gain of positive feedback)
good enough to assure the stability or do I need to make sure that the loop gain of the positve feedback loop to be < 1.

Thanks in advance,
hc

I agree with Tosei. To rephrase, when there are two loops, making certain the negative feedback loop gain greater than positive feedback loop gain will make the overall feedback, or the equivant single feedback, negative.

Rajesh