I'm working 5 hrs on this and still i dont get a clue at all.. Everything i tried is not working and i tried too much things in different ways, but i dont think these will help anyone.
This is the schematic of the pushpull follower amplifier that I want to calculate its thermal stability (I want to verify the thermal stability actually):
And this is the text where the authors analyze the thermal stability:
And my questions are:
1) How the voltage across R3 and R4 is raised by 20%???
2) In quiescent conditions the base current for Q2 will be: 0,6V / 470 ohm = 1 mA.
So the emitter current, assuming β=100, will be: 1mA * 100 = 0,1 A
From this we get an intrinsic resistance for Q2 with value: re = 25 / Ic =25 / 0,1 = 250 ohm, which is much bigger than the R3 and R4 values.
In which way these little resistor make such a big difference and shouldn't the authors take them into account in their calculations? Or they do take them?
This is the schematic of the pushpull follower amplifier that I want to calculate its thermal stability (I want to verify the thermal stability actually):
And this is the text where the authors analyze the thermal stability:
And my questions are:
1) How the voltage across R3 and R4 is raised by 20%???
2) In quiescent conditions the base current for Q2 will be: 0,6V / 470 ohm = 1 mA.
So the emitter current, assuming β=100, will be: 1mA * 100 = 0,1 A
From this we get an intrinsic resistance for Q2 with value: re = 25 / Ic =25 / 0,1 = 250 ohm, which is much bigger than the R3 and R4 values.
In which way these little resistor make such a big difference and shouldn't the authors take them into account in their calculations? Or they do take them?
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