#102 Noise Analysis quality improvments
I needed to use Noise Analysis and found a great deal of trouble, I think these suggestions can greatly affect the use of ngspice Noise Anlaysis
1) In Noise analysis currently we have to specify an ac source so that I have to do noise analysis, even if I only want output referred noise and so this is a waste of computation and unnecessary requirement.
Current workaround: dummy source
Proposed fix: Having 3 command flavours/options input reffered only, output reffered only, both
2) In Noise analysis the to get output reffed noise it has to be on a voltage node, in other words I have to measure output referred noise as voltage and not current, when trying to do noise analysis on MOSFET I want to get noise referred as Id.
Currrent workaround: Using CCVS (H) having vds as the control, -ve terminal to ground, +ve terminal disconnected and is the output for noise analysis.
Propesed Fix: have output be either voltage node, or a voltage source (measreing current in that source)
3) When Connect DC voltages source at output node the noise is measered to be 0 (V sourse treated as ac ground),
Current Workaround: high inductance L between V source and the output node
Proposed Solution: I am not sure if this is consdiered a problem, but I think it could have better described in the manual that all sources are treated with there AC value, or put an option in AC value to be open circuit or something.
These are general thing that I think could be furthere improved: saving op from any anlaysis, option to have values for anlaysis and not ranges (maybe input a vector), a way to name analsyis plot and not have it default numbering ex: op1 op2 op3, and as propsed before parameteric sweeps.
In the part where I was talking about general quality improvements I mentioned adding save op to any analysis, This is already implemented using .options KEEPOPINFO sorry for my confusion.
I forgot also to recommend save/print have a wildcard syntax especially when saving a lot of device parameters ex: when saving all 16 cap types in a mosfet, becomes too length two write, which exaggerated when doing this for multiple mosfets.