I need some help with calculation the biasing resistorvalues for the first stage

Question

I need some help with calculation the biasing resistorvalues for the first stage NPN transisitor. Specifications: VB = 0 (plus or minus .1v) IE = 1mA (plus or minus .1mA) The first stage is a common emitter amplifier with thefollowing: Vcc = 15v Vee = -15v = 255.9 I need some help with calculation the biasing resistorvalues for the first stage NPN transisitor. Specifications: VB = 0 (plus or minus .1v) IE = 1mA (plus or minus .1mA) The first stage is a common emitter amplifier with thefollowing: Vcc = 15v Vee = -15v = 255.9

Explanation / Answer

Since you did not provide a diagram, I'm assuming that the biasingresistors are connected from Vcc to Vee and form a voltage divider.In addition, I'm assuming that there is a resistor connected at theemitter. For VB = 0, both biasing resistors need to beequal. (R1 = R2) Looking back from the base, the thevenin equivalent is:VT = VB = 0, and RT = R1 || R2.Since R1 = R2, R1 || R2 = R1/2. Reflecting RT into the emitter, and writing thebase-emitter mesh equation 15V = Vbe + IERT/( + 1) +IERE 15V = 0.7 + (1mA)(R1/2)/(256.9) + (1mA)RE You can solve for R1 and thus R2, if you know RE, whichwill set Ic and thus Vce and is dependent on the voltage gain youwant. Let me know if I can clear anything up.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---