3D-RDL and Bondwire Technology Comparison for Implementation of a 10W Broadband Three-way LDMOS Doherty Power Amplifier

This paper presents a novel 3D-redistribution layer (3D-RDL) passive technology for a high-efficient broadband Doherty power amplifier (DPA). The comparison with the DPA reference based on bondwire technology is provided. The realized DPA in both technologies is based on the same integrated three-way Doherty LDMOS die and is assembled in land-grid array (LGA) package. The measured S-parameter, large-signal gain and efficiency are compared. Moreover, the linearized efficiency and adjacent channel power ratio (ACPR) will be reported for different output back-off (OBO). It will be shown through measurement that with 3D-RDL Doherty combiner, the efficiency dispersion at 8dB OBO is reduced by 3%-point over the band of 3.4 – 3.8 GHz, and the linearized ACPR with instantaneous bandwidth (IBW) of both 300 and 400 MHz is improved by 2.5 dB. With 41dBm saturated power, this miniaturized 4.5 x 4 mm2 LGA DPA is suitable for mMIMO base-station driver and small-cell applications.