US Patent 7596364 Merged low-noise amplifier and balun

An RF amplifier can include a differential inductor for single-ended-to-differential signal conversion. With a center tap of the differential inductor coupled to signal ground and the RF input signal coupled to one of the end taps of the inductor, the negative of the RF input signal is obtained at the other end tap of the inductor. The differential RF signal produced can be coupled to a differential transistor amplifier that has cross-coupling capacitances, improving the signal balance of the differential output signal.