We disclose apparatus which may provide power amplification in millimeter-wave devices with reduced size and reduced power consumption, and methods of using such apparatus. One such apparatus comprises an input transformer; a first differential pair of injection transistors comprising a first transistor and a second transistor; a first back gate voltage source configured to provide a first back gate voltage to the first transistor; a second back gate voltage source configured to provide a second back gate voltage to the second transistor; a second differential pair of oscillator core transistors comprising a third transistor and a fourth transistor, wherein the third transistor and the fourth transistor are cross-coupled; a third back gate voltage source configured to provide a third back gate voltage to the third transistor; a fourth back gate voltage source configured to provide a fourth back gate voltage to the fourth transistor; and an output transformer.