  In this paper we discuss the anatomy of frequency-domain gravitational-wave
signals from non-precessing black-hole coalescences with the goal of
constructing accurate phenomenological waveform models. We first present new
numerical-relativity simulations for mass ratios up to 18 including spins. From
a comparison of different post-Newtonian approximants with numerical-relativity
data we select the uncalibrated SEOBNRv2 model as the most appropriate for the
purpose of constructing hybrid post-Newtonian/numerical-relativity waveforms,
and we discuss how we prepare time-domain and frequency-domain hybrid data
sets. We then use our data together with results in the literature to calibrate
simple explicit expressions for the final spin and radiated energy. Equipped
with our prediction for the final state we then develop a simple and accurate
merger-ringdown-model based on modified Lorentzians in the gravitational wave
amplitude and phase, and we discuss a simple method to represent the low
frequency signal augmenting the TaylorF2 post-Newtonian approximant with terms
corresponding to higher orders in the post-Newtonian expansion. We finally
discuss different options for modelling the small intermediate frequency regime
between inspiral and merger-ringdown. A complete phenomenological model based
on the present work is presented in a companion paper.
