Hi:
I have attached a page from Malvino's text chapter 10 and a sim of the
circuit. The bias current through the two resistors is 2.38 mA as calculated.
However, the current through the two diodes is 1.35 mA. I don't understand.

I understand that if the diodes' IV curves match the IV curves of the
transistors, the quiescent collector current should also be 2.38 mA. It looks
like the curves don't match because Icq ≠ Ibias.

Even if you use the same transistor types as bias diodes, Icq ≠ Ibias (see
the second sim.

Thanks,

David

 

In the transistor there is such a parameter as Voltage Erly. If the collector voltage is higher, then the current is greater!
See the output characteristics of the transistor: collector current from the voltage Collector-emitter.