Common Emitter Amplifier DC analysis

Question

I have a standard common emitter amplifier biased using a voltage divider. I'm given that RE = 500 Ω, IC = 2.5mA, β=100, Vcc=15V and the coefficient of thermal stability K=10 (RE = K * Rth / (b+1) where Rth = R1//R2). I'm asked to calculate every current, voltage and resistor. I have calculate pretty much everything. IB=25μA, IC=IE=2.5mA (supposing IB<<IC), R1=38.55K, R2=5.81K, IR1=IR2=0.34mA (supposing IR1>>IB). VB=1.96V and VE=1.26V.

I'm unable to calculate with the data that I have VC and RC.

Also the Early voltage is -60V but I believe it is to be used later on for ac analysis.

Answer 1

Assuming an unstated (in your question) \$V_{_\text{BE}}=700\:\text{mV}\$, then:

^{simulate this circuit – Schematic created using CircuitLab}

With your \$K=10\$ factor, you should be able to find that \$X\approx 13.4\%\$. The rest, except for \$R_{_\text{C}}\$, falls out as shown above.

Assuming you want to set the collector voltage to somewhere in the neighborhood of \$8\:\text{V}\$ then \$R_{_\text{C}}\approx 2.7\:\text{k}\Omega\$.

That's all there is.

Answer 2

An here is the practical "result" ... with VEarly = 60 V.

With VEarly = 100 V, there is a "little" change.

And the TRansient should be this