adding white and flicker noise sources in cadence virtuoso

OK, to answer your first question, the answer is that you should not need to set the noise seed or scale factors. The noise seed just alters the initialization of the random number generators, so you will end up with a different sequence of random numbers, but they should have the same distribution. It's actually used if you use the "multiple runs" capability of transient noise to allow you to get a set of results to potentially average over (for example), but other than that I'd leave it alone. The scale factor just artificially increases the noise above what the model says it should be - so it's typically used for "what if" type investigations.

The problem could be that you don't have enough accuracy. Noise contributions are pretty small in general, and so it's quite likely you'll need to use errpreset=conservative at least (possibly setting reltol to 1e-4 as well, which would mean that the effective reltol is 1e-5 because conservative divides it by 10). It's also important to set a suitable value for noisefmax, so that you get noise contributions at high frequency. Note that if you don't set noisefmin, it will take whatever noise values there are at noisefmax, and use those across all frequencies (so effectively the noise will be white). If  you set noisefmin, it will be coloured using the power spectral density between noisefmin and noisefmax (this involves a bit more work for the simulator though, clearly). Also of course you need a long enough simulation to effectively see the contributions of low frequency noise.

To answer your subsequent 5 questions:

1. Whether you are doing small signal noise with acnames/actimes or using tran noise, it is including thermal noise.
2. I don't think small signal noise is really appropriate for an ADC. It's not going to include any noise folding caused by sampling - whereas transient noise would. You could potentially use pss/pnoise if the circuit is periodic in nature, but sometimes that can be difficult if you are performing a lot of conversion cycles of an ADC because it could take a lot of memory (pss/pnoise will capture the non-linearity in the pss, and hence your pnoise will include noise folding effects, but it's a small signal approach so a lot more efficient).
3. Can't say what your problem was here since you didn't say what the expression was or what the error was.
4. You can't use SpectrumMeas on the result of small signal noise - it uses a DFT approach and so the input has to be in the time domain, not frequency domain.
5. As I said originally, all that the actimes/acnames approach is doing is telling it to perform a small-signal noise at the DC operating point found at a specific point in time. That's fine if that's what you want, but I doubt it's what you really want here.

Regards,

Andrew.

OK, to answer your first question, the answer is that you should not need to set the noise seed or scale factors. The noise seed just alters the initialization of the random number generators, so you will end up with a different sequence of random numbers, but they should have the same distribution. It's actually used if you use the "multiple runs" capability of transient noise to allow you to get a set of results to potentially average over (for example), but other than that I'd leave it alone. The scale factor just artificially increases the noise above what the model says it should be - so it's typically used for "what if" type investigations.

The problem could be that you don't have enough accuracy. Noise contributions are pretty small in general, and so it's quite likely you'll need to use errpreset=conservative at least (possibly setting reltol to 1e-4 as well, which would mean that the effective reltol is 1e-5 because conservative divides it by 10). It's also important to set a suitable value for noisefmax, so that you get noise contributions at high frequency. Note that if you don't set noisefmin, it will take whatever noise values there are at noisefmax, and use those across all frequencies (so effectively the noise will be white). If  you set noisefmin, it will be coloured using the power spectral density between noisefmin and noisefmax (this involves a bit more work for the simulator though, clearly). Also of course you need a long enough simulation to effectively see the contributions of low frequency noise.

To answer your subsequent 5 questions:

1. Whether you are doing small signal noise with acnames/actimes or using tran noise, it is including thermal noise.
2. I don't think small signal noise is really appropriate for an ADC. It's not going to include any noise folding caused by sampling - whereas transient noise would. You could potentially use pss/pnoise if the circuit is periodic in nature, but sometimes that can be difficult if you are performing a lot of conversion cycles of an ADC because it could take a lot of memory (pss/pnoise will capture the non-linearity in the pss, and hence your pnoise will include noise folding effects, but it's a small signal approach so a lot more efficient).
3. Can't say what your problem was here since you didn't say what the expression was or what the error was.
4. You can't use SpectrumMeas on the result of small signal noise - it uses a DFT approach and so the input has to be in the time domain, not frequency domain.
5. As I said originally, all that the actimes/acnames approach is doing is telling it to perform a small-signal noise at the DC operating point found at a specific point in time. That's fine if that's what you want, but I doubt it's what you really want here.

Regards,

Andrew.