only SIN souce  has AC ? PWL and DC and any other no need to have such souce?

The AC option is required for any AC Analysis because it is the way in which spice runs a frequency domain sweep. Any Independent Voltage (V) or Current (I) Source may have the AC option appended to it. Except for the DC Offset supplied by the source, the AC option has nothing to do with how that V or I Sources are configured so the AC option can be appended to any DC/SIN/PULSE/EXP/SFFM/PWL configured V or I Source. The AC option cannot be applied to B, E, F, G or H sources. * Because of this bug it is not possible to set these simulation up in EasyEDA so here are some screenshots of sims in LTspice. I can send the LTspice files if required. This is a very simple example of the AC option appended to a V and an I source. Because the I source has a 1k load the AC option is set to 1mA (AC 1m 0) so that the voltage across R2 is 1V, the same as the AC 1 0 source created in V1. This makes both plots identical:  And this series of sim screenshots demonstrates what goes wrong if you assign the AC option to all sources in a circuit: This is a "conventional" frequency response of gain and phase from input to output so the AC option is applied to the input source I1 only:  This is the same circuit but measuring power supply rejection so the AC option is applied to the power supply V1 only:  But this shows that the results are meaningless if the AC option is applied to both the input and the supply sources, which is what is happeining at the moment in EasyEDA:  The appending of the AC option can only be chosen by the user because it is they who decide what they want to plot. It cannot be assumed which source or type of source that the AC option will be appended to. * Therefore appending of the AC option can not and must not be automated. I can send the LTspice files if required. The use of the AC option is explained in more detail here: [https://docs\.google\.com/document/u/1/d/1OWZVVFRAe\_2NW3WratpkA\_SGuHa5AcRow5ZRfvcoVTU/pub\#h\.vx1227](https://docs.google.com/document/u/1/d/1OWZVVFRAe_2NW3WratpkA_SGuHa5AcRow5ZRfvcoVTU/pub#h.vx1227)

AC\_Analysis\_02c\.asc above is effectively demonstrating the same thing that is happening to my AC Sweep bug example above in: [https://easyeda\.com/editor\#mode=sim\,id=\|8aae27aaf8d64096b407367892960681](https://easyeda.com/editor#mode=sim,id=%7C8aae27aaf8d64096b407367892960681)