  In this paper we have explored the consequences of a model of dark energy
with its energy density varying exponentially with the scale factor. We first
consider the model with $ \rho_{\phi} \propto e^{\kappa a} $, where $\kappa $
is a constant. This is a kind of generalisation of the cosmological constant
model with $\kappa = 0$. We show that such an exponentially varying dark energy
density with the scale factor naturally leads to an equivalent phantom field.
We also consider a model with $ \rho_{\phi} \propto e^{\kappa /a} $ and we show
that this also naturally leads to an equivalent phantom field.
