Hi,
In my VCO circuit, I want to do a layout. Anything comes from analog lib does not have layout view, like 'ind' 'cap'. When I replace the device of 'ind' by the 'spiral_std" (while keeping the inductance the same), the fundamental frequency gives similar values but the AC transient output waveform is way different. The output using the ideal device 'ind' has a large output swing which is good while using the later device, the output swing is almost 0, say varying from 1.1959V to 1.1961V, almost un-oscillating.
It seems there are large difference between the ideal inductance and the 'spiral_std" in terms of the modelling.
I also did similar experiment on ideal 'cap' VS the 'mim_cap" which has the size information like 'spiral_std' does.
With same capacitance value, I did not notice anything different. It means the modelling for those two are similar or at least the circuit is insensitive to the difference between them.
This is not the case for the inductor, which is a very large device in terms of geometry. I could think of many effects would be involved like parasitic resistance and capacitance.
In this circumstance, what should I do? Due to layout needs, how to use any non-ideal device like 'spiral_std' given the inductance value is already solved/known? Any extra compensation action I can take or I need to re-size the design or even re-design?
Kind Regards,
Alex