Ideally the one you're simulating for use in the circuit you're designing, generic single-pole amps don't work. The GBW is declared on the datasheet at that gives you Fc. For an NE5532 it's 10MHz for example with (IIRC and open loop gain of 120dB). A 741 is 1.5Mhz (as low as about 600KHz). Closing the loop applies some or all of that gain. For a 10x feedback (20dB) the closed loop gain drops by a factor of 10 so the more gain in the loop, the lower gain makes the phase shift less of a problem. I learned some of this using a popular model like the 741 in a stable (follower) circuit and you can see the internal pole at about 4Hz at full gain on a bode plot.
@@marcdraco2189 Yes, I agree. I will do that. I asked though, because I wanted to repeat your simulations in LTSpice and make sure I get the same or similar results before simulating with my own opamp. Will you tell me which opamp you used?
@@deanpalmer3211 I’m using a 5532 (in place of a Jenson 990). The 5532 is unusual because it’s output Rb is less than 1R. I had a good webpage but the site is down right now.
Why the open-loop gain could reach 120db after adding the inductor even when the Opamp is saturated at V+ and V-?
It is related to the internal circuit of the opamp. Check the transistors’ bias current at the output of the opamp.
What opamp is being used in the simulations?
Ideally the one you're simulating for use in the circuit you're designing, generic single-pole amps don't work. The GBW is declared on the datasheet at that gives you Fc. For an NE5532 it's 10MHz for example with (IIRC and open loop gain of 120dB). A 741 is 1.5Mhz (as low as about 600KHz). Closing the loop applies some or all of that gain. For a 10x feedback (20dB) the closed loop gain drops by a factor of 10 so the more gain in the loop, the lower gain makes the phase shift less of a problem.
I learned some of this using a popular model like the 741 in a stable (follower) circuit and you can see the internal pole at about 4Hz at full gain on a bode plot.
@@marcdraco2189 Yes, I agree. I will do that. I asked though, because I wanted to repeat your simulations in LTSpice and make sure I get the same or similar results before simulating with my own opamp. Will you tell me which opamp you used?
@@deanpalmer3211 I’m using a 5532 (in place of a Jenson 990). The 5532 is unusual because it’s output Rb is less than 1R. I had a good webpage but the site is down right now.