Input offset current/voltage

Thread Starter

mentaaal

Joined Oct 17, 2005
451
Mike, your attemps at helping me understand something so criminally simple whilst still keeping composure are valiant! I just had a look at it again after a good sleep and felt like kicking myself.

Thanks again Mike!
 

mik3

Joined Feb 4, 2008
4,843
ok.. perhaps one last question to annoy you with and i will understand... what if vin was negative.... is it possible that the bias current could flow through r1?
Yes and if you apply KCL at the inverting input node then you get:

Ibias=IR1-IRf
 

raybo

Joined Oct 18, 2008
22
there two sources of errors in a differential amplifier. mv which is related to the mis-match of input base to transistor diodes this will vary with amplifier to amplifier. Manufacture specs tells the ball park. the other source of errors come I f/b suppose pin [+] is gnd and the f/b is 1mohm or more then a current mis-match will occur in the input. by grounding the input the output should go to gnd. except for these conditions. to ceck these errors gnd the input and check the output. shorts the input and tie to a potential then you will see the common mode rejection .
 
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