Mitsubishi Electric and NanoSemi to demo ultra-wideband linearized Doherty amplifier for next-gen LTE base stations

In booth 201/300 at the IEEE Radio & Wireless Week (RWW2018) in Anaheim, CA, USA (15-16 January), Mitsubishi Electric US Inc of Cypress, CA, USA is presenting a hands-on mini lab showcasing its high-efficiency, wideband gallium nitride (GaN) Doherty amplifier.

At last year’s RWW2017 in Phoenix, AZ, USA, Mitsubishi Electric Corp and Mitsubishi Electric Research Laboratories Inc presented a paper ‘3.0-3.6GHz Wideband, over 46% Average Efficiency GaN Doherty Power Amplifier with Frequency Dependency Compensating Circuits’ describing this wideband Doherty power amplifier design technique for next-generation LTE base stations using GaN transistor technology. The demonstration at RWW2018 will further illustrate the ability to linearize an ultra-wideband signal applied to Mitsubishi Electric’s GaN power amplifier using an advanced pre-distortion technique provided by NanoSemi Inc of Waltham, MA, USA, which develops digital compensators to linearize non-linear dynamic systems such as wireless radios.

“The proliferation of smartphones and tablets will require a dramatic increase in wireless capacity of base stations,” says Kyle Martin, VP & general manager, Mitsubishi Electric US Inc Semiconductor Division. “To meet this demand, mobile technologies are moving to next-generation LTE in which the wireless capacities are increased by allocating multiple simultaneous frequency bands (carrier aggregation) above 3GHz,” he adds. “Operating in multiple simultaneous frequency bands usually requires multiple power amplifiers to cover each frequency band, leading to an increase in the size of base stations.”

Conventional base-station Doherty power amplifier design presents many challenges to simultaneously achieve both high efficiency and low distortion for wideband carrier aggregation. Using NanoSemi’s digital pre-distortion (DPD) technology, Mitsubishi Electric’s wideband Doherty power amplifier can achieve high efficiencies with up to 200MHz instantaneous bandwidth while maintaining adjacent channel level rejection (ACLR) of -50dBc. Base-station designers hence gain the ability to design a single flexible LTE power amplifier capable of many carrier aggregation scenarios, even above 3GHz, says the firm.

Mitsubishi Electric’s full line-up of GaN devices, with frequencies in cellular, Ku, and Ka-bands at output powers of 2-100W, supports a wide variety of end-communications applications including cellular base station, satellite, ground station and point to point.