Voltage for 0.18um?
Hi,
Actually, I'm not sure that such a formula exists,
0.8um--->5v (core/IO voltage usually is the same)
0.5um--->3.3v (core/IO voltage usually is the same or 3.3V/5V)
0.25um-->??? (2.5V - core/IO voltage usually is the same or 2.5V/3.3-5V)
0.18um-->??? (core/IO voltage is usually 1.8V/3.3-5V or even 1.8V/2.5-5V)
0.13um-->??? (core/IO voltage is usually 1.2V/3.3V or 1.2V/2.5V or in some shitty designs there are even 3 power supplies per chip 1.2V/2.5V/3.3V (I don't mean analog power in SOC systems, only digital))
For 0.13um and 90nm core voltage depends on process type, for example so called TSMC "general" process uses 1.2V, low-power, high density - 1.0V-1.1V, high-speed - even up to 1.5V, of course every one has its own libraries. For 90nm core voltages vary from 0.9V to 1.1V as far as I know.
You may look at @ltera or Xi|inx chips as a good example of the above.
Best wishes,
F.S.