I have a few questions about the circuit above. 1.This is an ordinary CE amplifier, which uses current mirror to provide temperature stabilization and bias for Q2, right? 2. Like Collector feedback bias and Voltage divider bias, this is just another way of biasing a transistor to provides temperature stabilization, correct? 3. If 2 is right, then does it have some advantages over the others? 4. Why are the 10k base resistors? Current mirrors seems to lack these. 5. How to calculate the resistors, for what voltage. Since it seems that there are two variations of this circuit, let's first talk about the one without the 180ohm emitter resistor. Since VBE is 0,7v, I assume that VB(orVC) must be atleast with 0,1v higher than VBE. So VB will be 0,8v, and across the base resistor( the 10k in this case) 0,1v will drop. So the equation for the base resistors will be Rb = VB-VBE/Ib= 0,8-0,7/Ib. About the 20k resistor, RC=Vcc-Vb/Ic+Ib1+Ib2= 20 - 0,8/ Ic+Ib1+Ib2. Is that right? And now with the emitter resistor. I've heard it's good to leave atleast 1v to the emitter. So, VC will be VE+VB=1+0,7=1,7V. From there, RB= VC-VBE/Ib=1,7-0,7/Ib= 1/Ib. RE=1v/Ie. That correct?