Interview with Pletronics: femtocell oscillator prices have dropped dramatically

pletronics_logoRakon have has cornered the market for femtocell crystal oscillators and timing solutions up to this point. The attraction of a growing and potentially enormous market has attracted other specialist suppliers, helping to drive costs down. Here, Pletronics explains the challenge of femtocell oscillators, provide some insight into current requirements and how the market will satisfy them.

What is Pletronics background and market position?

Pletronics has been in the crystal oscillator business since inception in 1979. Just like many other femtocell component specialists such as picoChip and Percello, we don’t currently own our production facilities.

We have a broad range of customers including military and leading internet equipment vendors. We are the preferred supplier to Cisco, Alcatel-Lucent and many other well known brands.

As a volume manufacturer with many other product lines, femtocells are a very small part of our overall business today, but one we expect to grow rapidly in the next few years.

How did you originally get involved with femtocells?

We had an early involvement with RadioFrame who are located nearby here in Washington State, and worked closely with them to meet the tight tolerances and low costs required.

Original timing solutions for femtocells were based on OCXO (Oven Controlled Crystal Oscillators) that cost up to $75 each. These designs were refined and the price point dropped to around $25.

Since then, TCVCXO (Temperature Compensated Voltage Controller Oscillators) have dramatically reduced the cost further, and we are now in the $4 range for volume orders. These consist of a package comprising crystal, IC (integrated circuit) and it’s enclosure – overall a much simpler construction than earlier OCXO devices.

The 3GPP standards reduced the tolerance required for frequency accuracy in Release 8. Has this helped?

While it’s true that the official standard specifications have relaxed the tolerance from 0.1ppm (parts per million) to 0.25ppm, operators continue to be cautious and conservative with their own specifications. We are seeing a dual specification come through from operators:

  • 0.1ppm in a narrow temperature range of 20-60 degrees Celsius
  • 0.25ppm in a wider temperature range of 0 to 70 degrees Celsius

Those femtocells destined for enterprise use have a tighter specification because they are not so price sensitive.

We expect there to be further relaxation of the operator’s specifications in order to meet the overall price points that are being demanded.

Why is the accuracy so important?

There are broadly two technical concerns:

  • Handover, when mobile handsets move into or out of the femtocell coverage area.
  • Densely populated zones with many femtocells (e.g. apartment buildings) where femtocells could interfere with each other.

For handover to work properly, the handset must quickly and accurately detect and switch between femtocell and macrocell carrier signals. If these are too far apart in nominal frequency, the handset may fail to detect and identify other basestations or lose the signal during the handover process.

What is the shape of the TCXO market for femtocells today?

Most of the industry players have become very specialized in recent years. Target markets include mobile phone handsets, GPS and SatNav gadgets. Pletronics has concentrated on military and instrumentation applications from which we are able to reuse the technology and expertise.

As the market for femtocells grows, everyone wants more than one supplier for critical components. The packaging for crystals is very similar between manufacturers – these can either be pin compatible or the femtocell board designs can incorporate a dual footprint. This approach would allow crystals from either supplier to be fitted during manufacturing.

The femtocell market for TXCOs is not unique. With their low cost, any OCXO application will be a potential target – this includes many instrumentation, military and communications products. We expect growth in demand for this type of product, although it would never become 100% of our business.

Do you provide a complete timing and synchronization solution?

A complete end-to-end timing and synchronization solution will combine a hardware crystal with specialist software algorithms that run on the femtocell’s main processor. There are a variety of vendors offering crystals, timing/synchronization software or both.

For example, Brilliant Telecom has firmware for IEEE 1588 synchronisation schemes which is claimed to work 50 times faster than alternatives. Many more schemes are evolving and new techniques are likely to appear in the future. We’ve seen more than 15 different papers on alternative approaches to solve this problem.

We believe that a best of breed solution comprises elements from each of these specialist areas. We’ve concentrated on being the best at the crystal oscillator and are happy to work alongside the rapidly evolving software solutions.

Are there any different requirements for the various RF technologies – CDMA, WCDMA or LTE?

Not really – the only impact is the nominal frequency used.

We see the femtocell market growing strongly and peaking in demand in about 3 years. Devices such as the iPhone and similar smartphones will require the traffic capacity and data rates that femtocells deliver.

Who are you working with today?

We’re actively engaged with the femtocell chipset vendors and also talking to several femtocell manufacturers. As with our other markets, we expect to be on the recommended/preferred supplier list as the market expands.

We are seeing several integrated femtocell products coming to market. Will this affect the way in which crystals are used?

There are a number of broadband modem and integrated set-top box manufacturers developing or investigating products that also incorporated femtocells. These will need the same crystal oscillators regardless of whether they are bought in modules from established standalone femtocell vendors or completely new in-house designs.

It’s very unlikely that the same crystal would be shared with other modules inside these boxes. It’s cheaper to add a separate crystal at a cost of 50 cents instead of adding the complex integration, extra FPGA chipset and PLL designs to derive different timing signals from the same oscillator.

And finally - how are your reaching your target market audience

We are in direct communication with the ASIC manufacturers and femtocell designers. We’ve tended not to exhibit with a stand at the large conferences, but were impressed with the networking opportunities afforded at the recent Femtocell Americas conference.

And of course our exposure through ThinkFemtocell will also raise our profile in the industry.

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