Patent ID: 10601375

Abstract:
A 3-stage Doherty amplifier that includes a three-way splitter, a carrier amplifier, first to second peak amplifiers, and an output combiner is disclosed. The output combiner includes first to fifth transmission lines with a λ/4 electrical length except for that in a downstream of the second peak amplifier, which provides a λ/2 electrical length. By dividing the latter transmission line into two parts each having a λ/4 length, and setting impedance thereof in a relation of (Z1/Z3)2×(ZL/3), the output impedance of the respective amplifiers are common to each other to be Zo, where Z1, Z3, and ZL are impedance of the transmission liens in respective downstream sides of the amplifiers, that of the transmission line provided in the output, and the load impedance, respectively.