Hi guys, What's the best way to get rms vdd potency (Real and Aparent)? I did: let pot= - i(vdd) *vd meas tran pot_rms rms pot from... (or something like that) Obs. : it worked, but i dont know if its the more safe way. Obs. 2: i dont know if i got a Apparent or Real potency with that code shown.

You are in the time domain. Do not calculate the

rms

value of a power. RMS is the (square root) average of squared values, taking the square of instantaneous power and taking the average is nonsense. If you want to get the average power do:

let pow = i(v1) * v(a,b)

meas tran cap_avg_pow avg pow from=600u to=800u

If

a

and

b

are the nodes of a capacitor and

i(v1)

is the current flowing into the capacitor in steady state the average power into the capacitor is zero. See example below. Instantaneous power into or out a capacitor is apparent, it has net value zero. See ngspice calculated value (in blue) at the bottom.