Electronic – Design a tuned common emitter amplifier

bjt

I'm getting stuck at the problem 2.16 in Art of Electronics.

"Design a tuned common emitter amplifier stage to operate at 100kHz. Use a bypassed emitter resistor, and set the quiescent current at 1mA. Assume Vcc is 15V, L = 1mH, and put a 6.2k resistor across LC to set Q = 10. Use capacitive input coupling."

schematic

simulate this circuit – Schematic created using CircuitLab

Is this a correct design? I found two way to find C:

1) f = 1/(2*pi*sqrt(LC)) ( and I know f = 100kHz, L = 1mH)

2) Q = w0 RC ( Q is 10, R is 6.2k, and w is based on f = 100kHz)

And they give different results. How could I solve this problem?

Best Answer

Your resistor needs to be 6.283K, then both methods will give you a value for C1 = 2,533 pf. It is only a matter of doing the calculations with higher precision components.