US Patent 7254380 Low flicker noise current-folded mixer

The current-folded mixer of this invention comprises an input stage and a switching stage. The input stage receives a radio frequency input RF and generates a modulated bias current to the switching stage. The switching stage has a switching pair, connected to a common node, to receive an input signal and said modulated bias current to generate an output signal in accordance with the input signal and the modulated bias current. The current-folded mixer uses a capacitor to separate the bias current of the input stage and the switching stage and an inductor in the switching stage to supply bias current.