Ultra wide-band linearized Doherty amplifier for LTE base stations
At Radio Wireless Week last year, Mitsubishi Electric Corporation and Mitsubishi Electric Research Laboratories presented a paper titled “3.0-3.6 GHz Wideband, over 46% Average Efficiency GaN Doherty Power Amplifier with Frequency Dependency Compensating Circuits,” that described this wide-band Doherty power amplifier design technique for next generation LTE base stations using GaN transistor technology.
The demonstration this year 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.
“The proliferation of smartphones and tablets will require a dramatic increase in wireless capacity of base stations. 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 3-GHz,” said Kyle Martin, VP and General Manager, Mitsubishi Electric US, Inc., Semiconductor Division. “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.”
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Conventional base station Doherty power amplifier design presents many challenges to simultaneously achieve both high efficiency and low distortion for wide-band carrier aggregation. Using digital pre-distortion (DPD) technology from NanoSemi, the Mitsubishi wide-band Doherty power amplifier can achieve high efficiencies with up to 200 MHz instantaneous bandwidth while maintaining ACLR of -50dBc. With this breakthrough, base station designers gain the ability to design a single flexible LTE power amplifier capable of many carrier aggregation scenarios, even above 3-GHz.
| Carrier Configuration | Efficiency | Output Power | ACLR |
|---|---|---|---|
| 100 MHz (5 LTE carriers x 20 MHz) | 47.9% | +34.0 dBm | -50.0 dBc |
| 160 MHz (8 LTE carriers x 20 MHz) | 46.2% | +33.9 dBm | -50.8 dBc |
| 200 MHz (4 LTE carriers x 20 MHz) | 47.5% | +34.2 dBm | -50.6 dBc |
| 200 MHz (10 LTE carriers x 20 MHz) | 44.4% | +33.2 dBm | -50.5 dBc |
Doherty Power Amplifier Performance at 3.5 GHz. Data measured at room temperature. Measurements may vary board to board.
Reference
[1] Yuji Komatsuzaki, Keigo Nakatani, Shintaro Shinjo, Shinichi Miwa, Rui Ma, and Koji Yamanaka, “3.0-3.6 GHz Wideband, over 46% Average Efficiency GaN Doherty Power Amplifier with Frequency Dependency Compensating Circuits,” 2017 IEEE Radio and Wireless Week, Phoenix, AZ.
https://us.mitsubishielectric.com/semiconductors/en/index.html
www.nanosemitech.com
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