Electronics > Beginners
opamp simulation
promach:
For the Improvements_in_biasing_and_compensation_of_CMOS_opamp (second reference link), why the author break open the connection between gates of M3A and M3B ?
And how to derive the inequality expression (14) in the document ?
Wimberleytech:
--- Quote from: promach on April 16, 2019, 10:32:15 am ---For the Improvements_in_biasing_and_compensation_of_CMOS_opamp (second reference link), why the author break open the connection between gates of M3A and M3B ?
And how to derive the inequality expression (14) in the document ?
--- End quote ---
Set P3 < P1 and simply do the algebra.
Eq 14 appears to have an error...should be gm2b in numerator, not gm2a
promach:
--- Quote ---Set P3 < P1 and simply do the algebra.
Eq 14 appears to have an error...should be gm2b in numerator, not gm2a
--- End quote ---
I will check your advice regarding the inequality expression, but why set P3 < P1 ? Is it dominant pole compensation or something else ?
I try to incorporate the author schematics (Figure 6 in the second reference link) into the opamp, but it resulted in erroneous bode plot
Which part is wrong in the schematics ?
Wimberleytech:
--- Quote from: promach on April 17, 2019, 03:00:49 am ---
--- Quote ---Set P3 < P1 and simply do the algebra.
Eq 14 appears to have an error...should be gm2b in numerator, not gm2a
--- End quote ---
I will check your advice regarding the inequality expression, but why set P3 < P1 ? Is it dominant pole compensation or something else ?
--- End quote ---
yes, essentially
--- Quote ---
I try to incorporate the author schematics (Figure 6 in the second reference link) into the opamp, but it resulted in erroneous bode plot
Which part is wrong in the schematics ?
--- End quote ---
ALWAYS check bias points before even looking at your ac response. In this case, your biasing is broken.
promach:
See the following circuit :
I am having problem using the miller lead compensation (M24 mosfet in triode region)
Any help ?
When I saw this 90MHz bandwidth opamp OPA838, I am inspired to do the same, but my current circuit bandwidth is only 10MHz.
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