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 Z0, 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.
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机译：公开了一种三级Doherty放大器，其包括三路分配器，载波放大器，第一至第二峰值放大器以及输出组合器。输出组合器包括具有λ/ 4电长度的第一到第五传输线，除了在第二峰值放大器的下游提供λ/ 2电长度的传输线。通过将后面的传输线分成两个分别具有λ/ 4长度的部分，并将其阻抗设置为（Z 1 / Z 3 ） 2 ×（Z L / 3），各个放大器的输出阻抗彼此公共为Z 0 ，其中Z 1 < / Sub>，Z 3 和Z L 是放大器各自下游侧的传输线阻抗，输出中提供的传输线的阻抗以及负载阻抗。
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