Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
The CMFB circuit should be included in the DC analysis to see the actual performance of your opamp, think this way, as the input DC voltage changes, the output DC voltage need to be compensated as well to get a proper gain, and this is done by adjusting the tail current source of the opamp.
True, your CMFB circuit acutally helps your circuit fix a DC point, over which your output sine wave is plotted. So most definitely you would want to stablize this DC point by adding your CMFB loop with your tail transistor (or whichever way you realized your CMFB loop). This will ensure the correct DC points !
Surely you will need it. Though, for a very first order simulation, if you need for example to verify the biasing of the amp, you can also connect to the outputs a DC source of the desired common-mode value. You can also realize the CMFB with controlled sources. Obviously, the OCM will be perfect (not real), but this is a faster way to begin. Then you will design and simulate the CMFB.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
