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Ooo! Ooo! I know! (picture little kid jumping up and down with his
hand in the air).<br>
The Vbe vs. Ic curves should be matched. I.e., for a given Vbe they
should give the same collector current, and visa-versa. The transistors
should be at the same temperature also since that greatly affects the
Vbe vs. Ic relationship.<br>
A two transistor current mirror will have an error due to the base
currents. One way you can decrease that error (by a factor of Beta) is
to add a third transistor with its B-E junction replacing the B-C short
on the "input" side of the mirror.The collector can go to the supply
rail (positive rail for npn mirror, negative rail for pnp) The
transistor doesn't have to match.<br>
Here's a link I found about current mirrors:<br>
<a class="moz-txt-link-freetext" href="http://www.eas.asu.edu/~thornton/Teaching/ece334/lectures/lecture_16.pdf">http://www.eas.asu.edu/~thornton/Teaching/ece334/lectures/lecture_16.pdf</a><br>
<br>
Paul Schreiber wrote:<br>
<blockquote type="cite"
cite="mid008001c3b44f$25bc0140$0201a8c0@speakeasy.net">
<pre wrap="">Yes, that's the whole *point* of being "matched" :)
Now, exactly WHAT is "matched" in a 'matched transistor pair'?
.....Anybody.....Buhler?........(yes, I know the answer, but I want you to find out yourself).
Paul S.
dang cold (cough cough)
----- Original Message -----
From: "Benjamin Riggs" <a class="moz-txt-link-rfc2396E" href="mailto:benj@iinet.net.au"><benj@iinet.net.au></a>
To: "Synth-Diy" <a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@dropmix.xs4all.nl"><synth-diy@dropmix.xs4all.nl></a>
Sent: Wednesday, November 26, 2003 12:41 PM
Subject: [sdiy] current mirrors
</pre>
<blockquote type="cite">
<pre wrap="">i am hardly an expert when it comes to transistor theory, but i think i
understand the basic operation of current mirrors. what i would like to know
is if in the basic two transistor curent mirror, do the transistors need to
be matched?
B
</pre>
</blockquote>
<pre wrap=""><!---->
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Scott Bernardi
<a class="moz-txt-link-abbreviated" href="mailto:sbernardi@comcast.net">sbernardi@comcast.net</a></pre>
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