On January 16-17, 2017, at booths # 1 and # 2 of Radio & Wireless Week (RWW2017) in Phoenix, Arizona, USA, Mitsubishi Electric Corporation is demonstrating a practical mini laboratory showing its high-efficiency wideband Doherty amplifier . In addition, at 10:50 am on January 16, the company submitted a technical paper describing Broadband Doherty (Session MO2D-3: '3.0-3.6GHz Wideband, over 46% Average Efficiency GaN Doherty Power Amplifier with Frequency Dependency Compensating Circuits'), reporting on power amplifier design technology for next-generation LTE base stations using Mitsubishi Electric's latest gallium nitride (GaN) transistor technology.
In order to break the inherent narrow-band limitation of the conventional Doherty design method, this paper proposes a frequency-dependent compensation circuit and an improved quarter-wavelength inverter containing parasitic elements of the transistor package.
Compared with earlier design methods, this compact design improves bandwidth and efficiency, providing an average power of more than 2.5W in the entire 3.0-3.6GHz band (20MHz LTE signal), with an efficiency higher than 45.9%. This enables the design of more competitive LTE amplifiers, enabling carrier aggregation scenarios in this frequency band. Combined with digital pre-distortion (DPD) to maintain an adjacent channel leakage ratio (ACLR) of -50dBc, the use of a broadband effective GaN Doherty design can reduce the complexity and energy consumption of the radio and further reduce the total number of base stations.
Mitsubishi Electric's full range of GaN devices, with output power ranging from 2 to 100W and frequencies in the L-, S-, C-, and Ku-bands, supports a variety of terminal communications applications, including cellular base stations, satellites, ground stations, and point-to-point.