Skyworks’ PA Geared to Support 5G Signals With Wide Instantaneous Bandwidth

Skyworks recently announced the release of SKY66318-11, a new addition to Skyworks' power amplifier (PA) family that is designed with small cells in mind.

Some of the key features of the SKY66318-11 include its power added efficiency of 20% at 28dBm as well as its wide bandwidth for 100MHz systems. This wide bandwidth is said to enable higher data rates for 4G and 5G signals

The SKY66318-11 comes in a compact 16-pin, 5mm x 5mm x 1.3mm package. It also includes on-chip active bias for gain tracking over variable temperatures, voltages, and processes.

The new PA supports a frequency range between 3.3GHz and 3.5GHz.

 

Block diagram of the SKY66318-11. Image from Skyworks

 

The SKY66318-11 is available on major transceiver reference designs and is a part of the Skyworks compatible PA family to support major 3GPP bands.  

 

A Comprehensive Network Architecture for 5G

One of the major challenges that researchers, engineers, and developers face involve designing small cells that can support and enable the expected capabilities of 5G networks.

According to IEEE's white paper titled, "5G and Beyond Technology Roadmap," the latest cellular network technology, 5G, is expected to deliver data rates 10s Mb/s for 10s of thousands of users. The data also predicts rates of 100Mb/s for metropolitan areas and 1Gb/s to workers on the same office floor.

The IEEE also predicts that, in addition to supporting thousands of connections for wireless sensors, 5G will improve coverage, enhance signaling efficiency, and reduce latency.

 

5G network architecture which includes massive MIMO networks and small cells. Image used courtesy of Akhil Gupta

 

In order to maximize the potential of 5G, developers must deploy a new, comprehensive network architecture. This 5G-based architecture must include massive MIMO networks and small cells, which SKY66318-11 aims to support. 

 

What are Enterprise Small Cell Environments?

Skyworks praises the new power amplifiers for its ability to meet the "stringent requirements of enterprise small cell applications." Understanding what "enterprise small cells" entails can shed light on the relevance of this claim.

Small cells have been deployed in many settings including residential, enterprise, urban, and rural environments.

Each small cell environment must meet region-specific demands: each cell environment has unique coverage capabilities to support different amounts of people, span various distances, and account for physical obstacles such as walls, buildings, or trees.

But in a report on improving wireless connectivity through small cell deployment, the GSMA specifies that enterprise environments are considered local area Base Stations (BS).

These enterprise settings include train stations, airports, retail stores, universities, and office spaces. The major challenge when delivering 5G to enterprise settings is ensuring reliable connectivity to the sheer volume of people that the network must support.

 

Medium-range BS in outdoor environments are often embedded in lighting fixtures, advertisement panels, bus shelters, or street signs. Image from GSMA

 

Still, Skyworks has expressed confidence that the PA has the wide instantaneous signal bandwidth (100MHz) to support such environments. 

 

Supporting Mid-band Spectrums

5G networks can be broken up into a low-, mid-, and high-band spectrum, all of which are supported by different frequencies. The SKY66318-11 falls into the mid-band spectrum—2.5GHz, 3.5GHz, or a 3.7GHz–4.2GHz range—with its operating range of 3.3GHz to 3.6GHz. 

The mid-band offers advantages that can be beneficial to enterprise networks, such as the ability for signals to travel over longer distances compared to mmWaves.

While the SKY66318-11 only covers a range of 3.3GHz to 3.6GHz, 3.5GHz is typically standard for many mobile operators and countries working on 5G developments.

 

Around the Industry

In order to understand how well SKY66318-11 is performing, we can look at several key metrics of a similar PAs—namely, their linearity, gain, and PAE.

Qorvo launched its own line of power amplifiers for small cell infrastructure. QUL9098 supports a 4GHz–6GHz operational bandwidth in a 2mm x 2mm package and offers 34% PAE with 19dB gain.

The PAE of this product is 14% greater than that of the SKY66318-11, but the gain falls short of the 34dB of Skyworks’ PA.

Both companies' power amplifiers promise high linearity and active biasing for high performance over temperature. One major disadvantage of the Qorvo PA is its inability to operate at the 3.5GHz band, which is where major 5G progress is being made.