Abstract: The invention relates to a frequency synthesis device comprising a direct digital synthesis device (22) for producing by calculation a signal oscillating at a determined frequency (Fdds), the calculation being performed by a logic circuit clocked by a clock signal (Sh) having a determined clock frequency (Fh), characterized in that it further comprises transposition means (74) for transposing the signal which oscillates at the determined frequency (Fdds) using the clock frequency signal (Sh), the signal thus transposed being supplied as an output (Sref).