Hi guys,
I am an IC designer, mainly designing chips for buck and boost converters. I use plain vanilla HSPICE for simulations - I have no fancy stuff like Spectre etc. at my disposal.
Recently I created a model of a buck converter for time domain simulations. I replaced all digital components of the chip with spice behavioural sources while keeping the analog components (current sense, error amp power train etc.) real. This helps me to do top level simulations in 1/50th of the time I would need if I just ran a simulation of the real chip at the top level.
Now I am toying with the idea of creating a frequency response analyzer in spice so that I can do a bode plot analysis on the (almost) real chip, instead of creating a averaged AC model. My idea is to use the method outlined by Dean Venable in his paper Testing Power Supplies for Stability
http://www.venable.biz/tp-01.pdfIn this he has described a way to inject a signal into the loop without breaking the loop. Of course he is talking about a real power supply where as I am referring to the spice model.
What I plan to do is inject AC signals of 10 different frequencies for every decade and check the amplification and phase of the output signal. Then plot the bode plot in excel. So if I want to run the sweep from frequency of 0.1Hz to 1Meg I would get gain phase sample at 70 different points. Since my model can run a simulation in 10 mins, I could finish the simulation in 700 mins = 11 hrs. The whole thing should be finished overnight.
What I would like to know is - Is this the best way of going about this or is there a faster way? Anyone tried anything like this before?
Cheers
krab