Warning from spectre during PNoise analysis 'pnoise'
WARNING(SPCRTRF-15092):The shooting small signal analyses (pnoise, for example) is unable to identify the primary oscillatory mode for the oscillator. Conditions that might cause this failure include:
1)circuit with both very large resistors and small resistors together,
2) circuits with very large capacitance or inductance, such as a DC block capacitor,
3)circuits with poorly designed macromodels.
To fix the problem, follow these steps.
1) Make the circuit reflect physical reality more closely. Avoid using very large inductance or capacitance values, such as C=1F
2)Avoid using very small floating resistors, particularly small parasitic resistors in semiconductors.
3) Try augmented=yes option.
WARNING (SPCRTRF-15227) : 4) Check the warning message issued during ntlisting and try to resolve all "no DC path" warning. Remove all foating components from the design.
5)Increase the Gmin value. Be sure, however, that the PSS waveforms do not change as a result, because that might indicate a loss of accuracy.
6)If the simulation continues to fail--with linear solver convergence warnings, for example--rn a harmonic balance (HB) PSS aalysis using the "augmented=yes" parameter setting.