| 摘要 |
A four-stage Doherty power amplifier includes a carrier amplifier (6), and first, second and third peaking amplifiers (14, 20, 24), the outputs of the amplifiers being coupled through an impedance network to an output node (10), wherein the carrier amplifier (6) is coupled to the output node through a first impedance inverting quarter wave transmission line stub (8), the first peaking amplifier (14) is coupled to the output node through second and third impedance inverting quarter wave transmission line stubs (16, 18) in order to provide a resultant non-inverting impedance between the first peaking amplifier and the output node (10), the second peaking amplifier (20) is coupled to a node between the second and third stubs (16, 18), and the third peaking amplifier (26) is directly coupled to the output node. The output node is connected to an output load (R L ) via an impedance transforming quarter wave transmission line stub (12). |
