The Opportunities and Challenges of LTE Unlicensed in 5 GHz
David Witkowski, Executive Director, Wireless Communications Initiative
In 1998, the Federal Communications Commission established the Unlicensed National Information Infrastructure or U-NII 5 GHz bands. These are used primarily for Wi-Fi networks in homes, offices, hotels, airports, and other public spaces and also consumer devices. U-NII is also used by wireless Internet Service Providers, linking public safety radio sites, and for monitoring and critical infrastructure such as gas/oil pipelines.

MMD March 2014

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Band Reject Filter Series
Higher frequency band reject (notch) filters are designed to operate over the frequency range of .01 to 28 GHz. These filters are characterized by having the reverse properties of band pass filters and are offered in multiple topologies. Available in compact sizes.
RLC Electronics

SP6T RF Switch
JSW6-33DR+ is a medium power reflective SP6T RF switch, with reflective short on output ports in the off condition. Made using Silicon-on-Insulator process, it has very high IP3, a built-in CMOS driver and negative voltage generator.

Group Delay Equalized Bandpass Filter
Part number 2903 is a group delayed equalized elliptic type bandpass filter that has a typical 1 dB bandwidth of 94 MHz and a typical 60 dB bandwidth of 171 MHz. Insertion loss is <2 dB and group delay variation from 110 to 170 MHz is <3nsec.
KR Electronics

Absorptive Low Pass Filter
Model AF9350 is a UHF, low pass filter that covers the 10 to 500 MHz band and has an average power rating of 400W CW. It incurs a rejection of 45 dB minimum at the 750 to 3000 MHz band, and power rating of 25W CW from 501 to 5000 MHz.

LTE Band 14 Ceramic Duplexer
This high performance LTE ceramic duplexer was designed and built for use in public safety communication and commercial cellular applications. It operates in Band 14 and offers low insertion loss and high isolation to enable clear communications in the LTE network.
Networks International

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August 2013

Is GaAs Really Dying?

By Liam Devlin, CEO, Plextek RF Integration

Liam Devlin, CEO, Plextek RF Integration

“The Death of GaAs?” —this was the title of a panel session at the June IMS2013 meeting in Seattle, and I have weighed the evidence and would like to discuss my thoughts.

The panel presentations largely focused on GaAs in cellular communications products, since this is the largest application—currently accounting for over 50% of all GaAs sales revenue. It is clear that the front-end switch function, which until recently was dominated by GaAs PHEMT devices, has now changed over to using silicon-on-insulator (SoI) technology. The reasons for this are that it gives comparable—or in some cases superior—performance, combined with the fact that all control logic can be included on the switch IC rather than requiring a separate CMOS control IC, as in the case of the PHEMT switches.

However, GaAs device sales are still growing in a subdued fashion—revenue was $5.3 billion in 2012, a modest 2% more than it was in 2011, but growth nevertheless. Interestingly, several companies that were founded to develop CMOS PAs have been acquired by GaAs vendors, among them Javelin, bought by Avago, and Amalfi, which was acquired by RFMD.

The PA function is still dominated by GaAs HBT, even in low cost handsets, despite the fact that CMOS PAs have been available for a number of years and are now used in some commercially available products. The panel provided data to show that although the cost per square mm of CMOS is cheaper than that of GaAs, the CMOS PAs occupy a larger area, so the resulting PAs are actually similar in cost. As GaAs HBT PAs also tend to offer superior efficiency, this has left them in a prime position for this function. The view that CMOS may become the technology of preference for entry level handsets, with GaAs HBT being preferred for higher-end products, was also expressed. However, panelist David Danzillio of WIN reported doing a tear-down on the cheapest cellular handset he could find on the street, which actually contained a GaAs PA.

Although the panel focused on the challenge of Si technologies to key applications for GaAs, the challenge from GaN was also covered. GaN technology is particularly well suited to the implementation of RF and microwave High Power Amplifiers (HPAs), an area of dominance for GaAs technologies. GaN is currently considerably more expensive than GaAs, but is capable of realizing HPAs with higher output powers and efficiency. The level of interest in GaN was clear across the conference and exhibition as a whole, but at the moment the higher costs mean that it is only used when GaAs capability runs out of steam.

Ultimately, end users purchase products based on a trade-off of price and performance rather than the elements used in the manufacture of the ICs. It is the market that will decide on the fate of GaAs, but the GaAs manufacturers and suppliers are still performing well and this doesn’t look set to end in the immediate future.

So is GaAs dying? I would say that my reply would be, “Not anytime soon, but the competition is increasing.”

About the Author
Liam Devlin is the CEO of Plextek RF Integration, a UK-based design house specialising in the design and development of RFICs, MMICs and microwave/mm-wave modules. He has led the design and development of over 70 custom ICs on a range of GaAs, GaN and Si processes at frequencies up to 90GHz. He has also developed microwave and mm-wave sub-systems using a variety of technologies. He was previously Chief Designer with Marconi Caswell where he designed GaAs ICs for both the commercial product line and for customer specific applications. Prior to this, Liam was employed by Philips Research Laboratories. He graduated from Leeds University in 1988 with a first class honours degree in electrical and electronic engineering and has published 40 technical papers.

Plextek RF Integration
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