THD = 20 lg(Vm/Vf) dB
where
Vm=√∞∑n=1V2n
Vn is the amplitude of the n-th harmonic component of the waveform and Vf is the amplitude of its fundamental component
THD = 20 lg(Vm/Vf) dB
V m = ∑ n=1 ∞ V n 2 MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHXgaruavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaeaaciWacmGadaGadeaabaGaaqaaaOqaaiaadAfadaWgaaWcbaGaciyBaaqabaGccqGH9aqpdaGcaaqaamaaqahabaGaamOvamaaDaaaleaacaWGUbaabaGaaGOmaaaaaeaacaWGUbGaeyypa0JaaGymaaqaaiabg6HiLcqdcqGHris5aaWcbeaaaaa@4186@