I am trying to create a TRL standard, but I am not sure what line lenght is correct to use.

According to "Network analysis appliyng the 8510TRL calibration for non-coaxial measurements", (pg 16) the optimal line length is chosen by

Electrical length(cm)=15/(f1(GHZ)+f2(GHz))

But I do not know if this length is the one that I fabricate "physically" or if I need to divide electrical length by the root square of dielectric constant of the substrate.

Also in delay offset I am not considering the dielectric constant...Is this correct?

All this is for on-wafer calibration..

Thanks!!!

Maria Fernanda

According to "Network analysis appliyng the 8510TRL calibration for non-coaxial measurements", (pg 16) the optimal line length is chosen by

Electrical length(cm)=15/(f1(GHZ)+f2(GHz))

But I do not know if this length is the one that I fabricate "physically" or if I need to divide electrical length by the root square of dielectric constant of the substrate.

Also in delay offset I am not considering the dielectric constant...Is this correct?

All this is for on-wafer calibration..

Thanks!!!

Maria Fernanda

You need to account for the effective dielectric constant of the substrate. The value of the effective dielectric constant is between the substrate permittivity and 1. The effective dielectric constant is a function of geometry as well as substrate permittivity. For example, the effective dielectric constant of a microstrip line differs from a stripline configuration.

You should take effective dielectric constant into account anytime you shift between electrical length and physical length. Thus TRL line standards should factor it in and offset standards should also factor it in.