What is "FI design" or "PHI design" when referring to semiconductors?

Question

I heard a bunch of semiconductor people referring to Fi design or PHI design, or maybe even Fy design. Does anyone know what this means and where I can learn more?

Thanks!

Answer 1

Are you sure they were talking about semiconductors?
They could have been talking about filters, or impedance matching circuits.

If the sequence of components is shunt-series-shunt then they look like the letter "pi". This is a PI filter. In 3-phase mains, it is called a "delta"

The other option, series-shunt-series is called a star, or Y, or "wye" filter.