Steve_IC
Junior Member
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Posts: 13
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attached is the opamp, I was having some questions( short channel)
1. the textbook and most people are talking about the ratio of M5 M7 and M3(M4) and M6. I was using bsim3 level 1 model without any problems, but transfer to cadence tools, with more sophiscated model, either m7 or m6 will be out of sat region, I have to resize m6 or m7, could not keep the ratio anymore. anyone has such experience, and any guideline? what's more, I found sometime a slight change of either m7 or m6's size, will make either one out of sat region. I was worrying that any process variations(10%-30% during fab) would make my design not work. someone told me feedback could solve this problem? is it true?
2. regarding the current mirror, theoretically, with adjusting the size ration m10 and m5 and m7 and m9, we should be able to get the desired current, but in the simulation, to be able to get desired current, I still need readjust the size of m5,7, 9. or either use cascode to get desired current. any comments?
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