Sorry, please refer to the new attachment.Originally posted by hgmjr@May 12 2005, 09:31 PM
I may be wrong but the schematic you have posted looks a bit odd.
The two resistors labeled Re are in parallel and both ends of these two resistors are tied to ground. That pretty much means they have nothing to contribute to the circuit.
Also the amplifier looks like it might be an opamp. If that is the case, then it would be helpful to indicate which input is the negative one and which is the positive one.
There is no need for a feedback network. This is just a typical difference amplifier application but done with an op-amp. If you remember, the op-amp's input is 2 Darlingtons connected in via differential input.Originally posted by mozikluv@May 16 2005, 10:23 PM
where is the feedback network?
This question is on a distance learning course and is only covered by a description within the unit.Originally posted by Brandon@May 18 2005, 07:07 PM
There is no need for a feedback network. This is just a typical difference amplifier application but done with an op-amp. If you remember, the op-amp's input is 2 Darlingtons connected in via differential input.
Telling you how to find the CMR is some technical data that got pushed out by other crap. Maybe if you attempted to redraw it into a format like what ever you covered in class for CMR.
Mm.....Originally posted by magnet@May 19 2005, 01:57 PM
This question is on a distance learning course and is only covered by a description within the unit.
I you know how to help or where I may find information on this, especially where calculations are involved, it would be greatly appreciated.
This question is a bit puzzling because all references about CMR equations are to do with the Voltage. The hint within the question was to add minimal resistor values!!Originally posted by Brandon@May 20 2005, 04:15 PM
Everything I have is for the transistor level and without knowing Betas/gm of the xtrs I couldn't give u my equasions to solve for it.
You could possible take a different approach to solving this tho. CMR is just the diff mode gane / common mode gain. You can simulate both of these situations and divide the resulting gains and get an approximate answer. Just put a differential input, say 5v and 0v, and then a common mode input, 4v and 4v or so.
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by Jake Hertz
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