# Transitor circuit help

• Engineering
• Myrddin

## Answers and Replies

Doing practice exam papers for electronics module, can someone explain to me how to go about this question?

http://img402.imageshack.us/i/electronicsquestions.jpg/

What do you know so far for how to bias a Common-Emitter (CE) BJT voltage amplification stage? Do you understand how to do the basic biasing, and are asking where the bandwidth portion of the question comes in? Or are you not familiar with BJT biasing at all?

If it's just the bandwidth part of the question, you have an input signal coupling capacitor, and the bias circuit & BJT together present an input impedance. What kind of filter does that form for input signals coupled to the input capacitor?

Have you been given information about the type of transistor used, or details of its characteristics, particularly its current gain and its base-emitter voltage?

Do you have any values for the DC conditions required, such as the collector current, the collector voltage (Vc in the diagram), or the emitter voltage?

The question page you have posted does not show any of this information, so unless you were given it elsewhere, you need to begin by choosing reasonable values. Can you do that?

Thats the whole question. I see there's a potential divider to find the values of resistance for Rb1 and Rb2, what i don't know know is what it means to "bias the amplifier". I am very unfamiliar with transistor circuits know only the very basics, the collector the base the emittor. Know that Vemitter = Vbase -0.6volts, and that its assumed that Ic = Ie as some rules of transisotrs.

From some notes iv got "Want Vcollector = 0.5 (Vin)" , is that what's needed to "bias the amplifier" ? if so i think can do it using those transistor rules and the fact there's a potential divider.