Abstract: A method for converting a real signal into a complex signal in quadrature, whose particularity consists of the fact that it comprises the step that consists in adding to a real signal meant to be converted into a complex signal a signal whose frequency is four times the band-center frequency of the signal to be converted, in order to obtain a quadrature. The method further comprises the steps of: after the adding step from which a sum signal is obtained, selecting, from the sum signal, a first component and a second component which are in phase and in quadrature; removing components below a given level from the first and second components in phrase and in quadrature, in order to obtain a first and a second signal component at DC zero level.