RF power solutions for small cells

Jon Lawson

NXP wirelesss chip spin-out Ampleon has launched a wide portfolio of RF power devices for medium power and massive-MIMO applications. These applications include LTE pico- and micro-cells as well as multiple-antenna array (LTE-Advanced Pro and 5G) systems. The devices support all cellular bands from 700 MHz to 3.8 GHz in a range of forms from dual-stage MMIC modules to fully integrated multi-stage Doherty power amplifiers (PAs) matched to 50 Ohms.

A 12 V LDMOS MMIC process has been developed for pico-cells and amplifiers covering 0.25 W to 2 W at the antenna offering the best compromise between performance and power density. The 12V process provides wider band solutions, compared to a 5 V process, and allows an easier design of high-efficiency amplifiers such as Doherty. These MMICs are housed in the compact and cost-effective plastic DFN package.

The BLM9U2327-5B is an example device that is currently available as engineering samples.

For micro-cells, typically 4 to 10 W, the devices include dual-path MMICs to provide the most flexibility in Doherty design and are available in both symmetric and asymmetric versions, for all cellular frequency bands. These MMICs are designed with bandwidth and Doherty requirements in mind, covering multiple bands and providing a typical isolation of more than 27 dB between the main and peak transistors.

Devices already in mass production include the BLM8G0710S-45AB, the BLM7G1822S-40AB and the BLM8D1822S-50PB, while the BLM8G2327S-40PB and BLM9G3438-25B are currently available as engineering samples.

For high-performance and ultra-wide band applications, single stage integrated Doherty’s are being sampled. Depending on the requirements, a single device can be offered covering for instance 1.8 to 2.2GHz in a single fixture, with an efficiency better than 45%. In a single-band application the efficiency will exceed 50%.

The BLF8D1822LS-80, BLC8AD1822LS-80P and BLC8D1822LS-160P are currently available as engineering samples.

For massive antenna systems such as LTE-Advanced Pro and 5G antenna arrays where size is even more critical, integration and ease-of-use comes from multi-stage Doherty PAs matched to 50 Ohms. These are housed in compact and cost-effective plastic PQFN packages. These use the latest LDMOS and GaN processes, depending on the frequency band. LDMOS is used up to 2.7 GHz while quarter-micron GaN is used for higher frequencies. These integrated PAs are currently being sampled and will be more widely available from the second half of 2016.

Ampleon, based in Nijmegen, Holland, was spun out of NXP in 2015 to exploit the full potential of data and energy transfer in RF and has more than 1,250 employees worldwide targeting cellular base stations, radio/TV/broadcasting, radar, air traffic control, cooking, lighting, industrial lasers and medical applications.