Hello,

I'm computing stability margins of a system.

The phase margin (PM) is computed correctly, but the gain margin (GM) shows zero (actually it shows 1E-16).

Analyzing the bode plot of the open-loop (OL) transfer function, it clearly shows that the GM should be infinite, since the phase of the

OL never crosses the -180 deg line (it only converges to it asymptotically as omega approaces infinity).

See below the bode plot of the OL, including stability margins.

Any idea why it happens?

Thanks,
-Shai