transistor common emitter

please help
who can help me determine the variables in this electronic assembly?
thank you

Hello,

You should do your homework yourself, but:

Rc = u/I = 3/0.5m = 6kOhms.

From the bias point, you can have 3V swing up, so you want also 3V swing down (actual collector voltage 3V during negative peak of input signal). So 2V across the emitter is a good starting point.

Neglect Ib, so Re = u/I = 2/0.5m = 4kOhms.

Because of Vbe, Vb will be about 2+0.6 = 2.6V.

Take current through base bias resistors about 10 times Ib (to avoid temperature drift due to temperature dependence of HFE and spread over devices).

Ib = Ic/Hfe = 0.5m/100 = 5uA, so current through bias resistors 50uA.

R2 = 2.6/50uA = 52kOhms, R1 = (9-2.6)/55uA = 116 kOhms.

Impedance seen from emitter capacitor (your Cd): "//" means "parallel"
This is Re//re re IS NOT RE
Gm = 40Ic = 0.02, so re =50 Ohms
50//4k = 50Ohms.

Taking 20 Hz –3 dB corner results in Cd = 160uF (R*C*2*pi*f = 1).

Input impedance is about 1/40ib = 1/(40*5u) = 5kOHms

Total input impedance = 5k//52k//116k = 4.4 kOhm
Taking same 20 Hz corner, Ce = 1.8uF.

In a real circuit you will also add high frequency cut-off to avoid interference from radio sources.

Hopes this helps you a bit forward, be aware of mistakes.

Added after 4 minutes:

By adding a resistor in series with Cd, you can set the gain of the circuit.

Gain (without additional loading) = -Rc/(Res+50)

Res = additional resistor in series with Cd.

As this raises the impedance seen from Cd, Cd can have a smaller value, also distortion will reduce due to the feedback from the additional resistor.