Common Base Circuit help

Dec 14, 2004 4 Replies

I need to design an amplifier.



The specs are:



use a 2n3904 AC gain 20 outut resistance 20k input resistance 2k suply volt 15v collector to ground needs to be 7.5


I believe the best way to do this is common base because there isn't a negative gain and with a common emitter I wouldn't be able to achieve such a low ac gain, right????


any assistance would help. I've been working on this for a few hours now.


in article Quqvd.189094$V41.5416@attbi_s52, Bob at snipped-for-privacy@private.com wrote on 12/13/04 4:30 PM:

I almost got suckered into sending you the answer to this question. Then I realized that it probably was a homework problem. using the 2N3904 and the nice round numbers gave you away. So this is what I will do.

In about two weeks, if I remember to do so, I will post the answer. Meanwhile, you can tell the instructor that no one was willing to do your work for you.

Bill

I don't remember asking for the answer. I just remember asking for some assistance. But since you responded in such a rude manor, you must have saw your name in the sentence "ASS"istance and decided to post something stuipd.

Don't worry about "waiting a few weeks", it's part of a project that I need to have done this week and I was a bit confused. I clearly understand what a common base and emitter is, I just needed a little help.

Good job keeping the newsgroup going as a help section! hopefully others wont follow in your footsteps and they will stay mature as usual.

Now might be an appropriate time to send this in. It has been delayed in order to prevent it being used for homework or a tqakehome exam.

in article Quqvd.189094$V41.5416@attbi_s52, Bob at snipped-for-privacy@private.com wrote on 12/13/04 4:30 PM:

Wrong! I presume you mean voltage gain of 20. Use a common emitter configuration. The emitter resistor should be 1K, the collector resistor

20K. That sets the gain and output resistance using negative feedback. I will leave it to you to figure out what to do for you input circuit.

Bill

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