Power Combining Configurations of HPUE PA for 5G Mobile Phone Applications

With the spread of 5G (5th generation) mobile phones, increasing the output power of PAs (power amplifiers) will become an important issue. From the viewpoint of power combining, a differential PA capable of increasing the output voltage amplitude is attracting attention. In the case of differential operation, it is possible to set a load impedance four times that of a single-ended PA with the same output power, which reduces the loss due to the parasitic resistance of the OMC (output matching circuit) and at the same time realizes a wider matching bandwidth. The transformer matching circuits have been widely studied as a matching circuit suitable for differential PA. The transformer matching circuit can easily realize differential/single conversion. For this reason, transformer matching circuits are an essential technology for differential PAs. In this report, we compare typical power combining configurations and clarify the advantages of differential PA. We also compared the matching bandwidth of the CL-LC matching circuits with the basic transformer matching circuits in which the input/output shunt capacitance is added to the transformer. As a result, it was shown that although the matching bandwidth of the transformer matching circuits are slightly narrowed, it is possible to realize a matching bandwidth that is comparable to the CL-LC matching circuits.