A high-efficiency single-to-differential amplifier has a first transistor acting as a first amplification stage. A second transistor, a third transistor, a first choke, a second choke, and a first capacitor form a second single-to-differential amplification stage. The first amplification stage receives and amplifies an input signal, outputs the amplified signal to the second single-to-differential amplification stage through a coupling module, and concurrently provides DC bias current to the second single-to-differential amplification stage through a tank. The second single-to-differential amplification stage reuses DC current of the first amplification stage, amplifies the output signal of the first amplification stage, and transfers it to a differential output.