A differential mixer including at least two input/output stages, each stage including two identical branches, each branch of one of the two stages including at least two bipolar transistors the bases of which define a first pair of input/output terminals of the stage and are connected to a same D.C. current source individually by a respective isolating resistor; the collectors of which define a second pair of input/output terminals of the stage which forms a pair of input/output terminals of another stage of the mixer; and the emitters of which are individually connected to a low voltage reference line by a respective degenerative impedance.