The present invention includes a mixer circuit integrating a voltage-to-currrent conversion in the same stage. A mixer device 20 of a transmission system comprises a pair of transistors 41 and 42 forming a differential circuit having two differential inputs receiving a carrier V.sub.LO, two differential current outputs delivering a differential output current and a common current output whose current is equal to the sum of the differential output currents; a current-to-voltage conversion element 47 coupled to the common current output of the pair of transistors; an amplifier 30 having a positive input receiving the modulating signal, a negative feedback input coupled to the current-to-voltage conversion element, and an output coupled to each of the differential inputs of the pair of transistors.