sir, For asic layout, i need guidance regarding metal width for 50 ohm single ended impedance and metal width and spacing for 100 ohm differential impedance: My pdk has info regarding Resistance per unit length based on different widths of the metal layer. That should help for 50 ohm single ended impedance. But to my knowledge, metal layer spacing also affects differential impedance

I believer you want to calculate 50 ohm impedance for transmission lines. Metal width alone (along with dielectric height and permittivity) determines the geometry-dependent Z0; your PDK’s resistance per unit length helps model conductor loss but doesn’t directly set the impedance. For 100 Ω differential impedance, both metal width and spacing are critical; spacing controls coupling and affects odd-mode impedance. Use EM tools or field solver-based calculators with your PDK’s dielectric and metal stack parameters for accurate calculations.

Thank you sir!