A millimeter-wave wideband frequency doubler stage for use in a distributed frequency doubler includes: a differential input pair of transistors, each transistor having respective gate, drain and source terminals, wherein the source terminals are coupled together to a first power supply node and the drain terminals are coupled together at a first node to a second power supply node; first and second pairs of bandpass gate lines coupled to the gate terminals of the transistors; and a pair of bandpass drain lines coupled to the drain terminals of the transistors.