  The recently released BICEP2 data detected the primordial B-mode polarization
in the Cosmic Microwave Background (CMB) map which strongly supports for a
large tensor-to-scalar ratio, and thus, is found to be in tension with the
Planck experiment with no evidence of primordial gravitational waves. Such an
observational tension, if confirmed by forthcoming measurements, would bring a
theoretical challenge for the very early universe models. To address this
issue, we in the present paper revisit a single field inflation model, which
includes a modulated potential. We show that this inflation model can give rise
to a sizable negative running behavior for the spectral index of primordial
curvature perturbation and a large tensor-to-scalar ratio. Applying these
properties, our model can nicely explain the combined Planck and BICEP2
observations. To examine the validity of analytic calculations, we numerically
confront the predicted temperature and B-mode power spectra with the latest CMB
observations and explicitly show that our model is consistent with the current
data.
