MMIC-based asymmetric Doherty power amplifier for small cells applications

Abstract

We present the results obtained on a multi-mode multi-band 20 W Monolithic Microwave Integrated Circuit (MMIC) power amplifier. The proposed two-stage circuit is based on the silicon Laterally Diffused Metal Oxide Semiconductor (LDMOS) technology. Thanks to dedicated design techniques, it can cover the Digital Cellular Service (DCS), Personal Communications Service (PCS), and UMTS bands (ranging from 1.805 to 2.17 GHz) and deliver more than 20 W of output power, 30 dB of gain and 50% of power added efficiency. When combined in a Doherty configuration with an incremental 40 W MMIC in a dual-path package, the resulted asymmetric MMIC (an industry first) can deliver an unprecedented LDMOS MMIC efficiency of up to 44% at 8 dB back-off in the UMTS band. Then, the DPA has been optimized in conjunction with a novel RF pre-distortion technique, leading to 33–80% energy saving at the system level.

A 280 W LDMOS broadband Doherty PA with 52% of fractional bandwidth based on a multi-line impedance inverter for DVB-T applications

“…Although GaN-based DPA permits high frequency (above 2 GHz) with wideband operation, and GaN devices on Silicon substrate are promising for lower cost, significant technological efforts are needed before they could be exploited in the below 1-GHz terrestrial digital video broadcasting (DVB-T) applications, which are addressed in this paper. In this respect, a cost-effective device technology for RF broadcasting applications is represented by the Silicon laterally diffused metal oxide semiconductor (LDMOS) device technology [13], mainly due to its high gain (20 dB at 2 GHz), good efficiency, inherent linearity, excellent reliability, ruggedness, and low cost [14]. These features make LDMOS the technology of choice for the development of DPA for broadcasting applications.…”