Assume two bipolar transistors in a PTAT are biased at a current-density ratio of 8 : 1 at . What is the difference in their base-emitter voltages and what is its temperature dependence?  Assuming and...

Assume two bipolar transistors in a PTAT are biased at a current-density ratio of 8 : 1 at . What is the difference in their base-emitter voltages and what is its temperature dependence?

 Assuming and using (7.25), what is the value required for in order to get zero temperature dependence at for a current-density ratio of 8:1 in the two transistors?