Comparison of Bandwidth Extension Methods for Doherty Power Amplifiers for 5G

A review of Doherty power amplifier and load modulated balanced amplifier for 5G technology

“…This stub adjusts the impedance that is connected to ZT and makes up the impedance drop that the carrier amplifier experiences. Similar effects is observed when connecting a parallel LC to the combiner node 53,54 …”

“…36 Also, the bandwidth enhancement approach is implemented by altering the DPA Figure 12 and connecting a parallel LC resonator to the combiner node or, a series LC resonator to the main amplifier branch in the case of existing a transmission line before load. 54 DPAs will show less impedance variation versus frequency if a λ=4 short-circuited stub line is added to the traditional load modulation network (Figure 13), consequently the DPA bandwidth will increase. This stub adjusts the impedance that is connected to ZT and makes up the impedance drop that the carrier amplifier experiences.…”

“…Similar effects is observed when connecting a parallel LC to the combiner node. 53,54 Another approach to address the bandwidth limitation in DPAs is using voltage-combined DPA structures (Figure 14A). Voltage-combined DPAs have a reduced ITR from 50 to 2R opt compared to traditional current combined DPAs, and this leads to a higher bandwidth in voltage-combined DPAs.…”

“…F I G U R E 1 3 Modifying the load modulation network 53 F I G U R E 1 4 (A) Voltage-combined DPA. (B) Bandwidth-enhancement technique 54…”

“…Also, the bandwidth enhancement approach is implemented by altering the DPA Figure 12 and connecting a parallel LC resonator to the combiner node or, a series LC resonator to the main amplifier branch in the case of existing a transmission line before load 54 …”