Question is in following:

In the Eqn.56 of Ken's paper(noise and jitter)

var(n)=∫₀^∞S_n(f)df

However, in the paper "Jitter and Phase Noise in Ring
Oscillator" of Hajimiri in 1999, the jitter is calculated by

σ_ΔT²=∫₀^∞S_Φ(f)sin²(πfΔT)df

if the ΔT→∞ then

σ_ΔT²=2/(ω₀²) ∫₀^∞S_Φ(f)df
Who can help me to understand, why the two transformations are different,
and how to explain it? Thanks a lot in advance!