The present invention relates to a device for neutralization of a signal obtained by transposition to a high frequency of a useful signal supplied by a unit of equipment, the said equipment having a spurious capacitance Cparasite that varies over time. The device comprises a neutralization capacitance Cneut and means with adjustable gain G, together with means for feedback controlling the gain G in such a manner that, continuously, G×Cneut=Cparasite.