  The effective action for local composite operators in $QED_3$ is considered.
The effective potential is calculated in leading order in $1/N_f$ ($N_f$ is the
number of fermion flavors) and used to describe the features of the phase
transition at $N_f=N_{\rm cr}$, $3<N_{\rm cr}<5$. It is shown that this
continuous phase transition satisfies the criteria of the conformal phase
transition, considered recently in the literature. In particular, there is an
abrupt change of the spectrum of light excitations at the critical point,
although the phase transition is continuous, and the structure of the equation
for the divergence of the dilatation current is essentially different in the
symmetric and nonsymmetric phases. The connection of this dynamics with the
dynamics in $QCD_4$ is briefly discussed.
