Considering the ac base resistance can pro-
vide a more accurate estimate of differential
gain. However, it may not be necessary. Since
we used the conservative 50-mV value for es-
timating re. the gain will probably be closer
to 50 for Fig. 9-9. Designers often use at very
conservative approach to ensure that the ac-
tual circuit gain will be at least as high as their
calculated value. Too much gain is an easier
problem to solve than not enough gain.