Sur certains complétés unitaires universels explicites pour GL_2(F)

In this paper we give an explicit description of the universal unitary completion of certain locally Q_p-analytic representations of GL_2(F), where F is a finite extension of Q_p (this generalizes some results of Berger-Breuil for F=Q_p). To this aim, we make use of certain Banach spaces of C^r functions on O_F (for r a positive real number) introduced by the author.