It seems to me, that in most applications we wouldn't want to be slew rate limited. That is, we would want to hit the 3dB corner (f_3dB), or the full power BW, before we hit the slew rate frequency (f_SR). We can check if this is the case from the op-amp's data sheet, which gives us its GBP (gain-bw-product) and its SR (slew-rate). We have: GBP = (A_CL)(f_3dB) or f_3dB = GBP/A_CL. We also have SR = 2(pi)(Vout_pk)(f_SR) , or f_SR = SR/((2pi)(Vo_pk)). Using Vo_pk = (Vin_pk)(A_CL) this last equation can be written as f_SR = SR/((2pi)(Vin_pk)(A_CL)). So we need f_SR > f_3dB, or SR/((2pi)(Vin_pk)(A_CL)) > GBP/A_CL, or SR/((2pi)(Vin_pk)) > GBP. If this isn't true then our application needs an op-amp with a larger SR and or a smaller GBP (or we need a redesign where we start with a smaller input signal Vin_pk). Am I thinking about this correctly? Thanks!! And beautiful job on teaching about closed loop f_3dB and SR !!.
These videos are really great, thanks for making them, seriously. I do have one question: When I attempt FFT, I do not have the same parameters available that you have. For instance, I have no "Window function" or anything below "Number of Points". I have the latest version of LTSpice for MacOS (Version:17.0.21.0). I've searched for this info elsewhere to no avail. Is this something simple I am missing?
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You explain way better than my teacher ! Thank you :D
It seems to me, that in most applications we wouldn't want to be slew rate limited. That is, we would want to hit the 3dB corner (f_3dB), or the full power BW, before we hit the slew rate frequency (f_SR). We can check if this is the case from the op-amp's data sheet, which gives us its GBP (gain-bw-product) and its SR (slew-rate).
We have: GBP = (A_CL)(f_3dB) or f_3dB = GBP/A_CL. We also have SR = 2(pi)(Vout_pk)(f_SR) , or f_SR = SR/((2pi)(Vo_pk)). Using Vo_pk = (Vin_pk)(A_CL) this last equation can be written as f_SR = SR/((2pi)(Vin_pk)(A_CL)). So we need f_SR > f_3dB, or SR/((2pi)(Vin_pk)(A_CL)) > GBP/A_CL, or SR/((2pi)(Vin_pk)) > GBP.
If this isn't true then our application needs an op-amp with a larger SR and or a smaller GBP (or we need a redesign where we start with a smaller input signal Vin_pk). Am I thinking about this correctly? Thanks!! And beautiful job on teaching about closed loop f_3dB and SR !!.
These videos are really great, thanks for making them, seriously. I do have one question: When I attempt FFT, I do not have the same parameters available that you have. For instance, I have no "Window function" or anything below "Number of Points". I have the latest version of LTSpice for MacOS (Version:17.0.21.0). I've searched for this info elsewhere to no avail. Is this something simple I am missing?
Awesome video, thanks for the insight.
Thank you. I am glad you found it insightful!
Well done.
Excellent Thanks
Hi, how do I generate the system of equations for a drawn circuit, please?
Many thanks ;)
A thousand likes if I could! Thank you! Thank you!
David Corredor I’m glad you liked it!