editor's blog
Subscribe Now

Tunable RF

One of the more delicate parts of a cellphone is the RF circuitry responsible for getting the signals into and out of the phone.  According to UCSD’s Prof. Gabriel Rebeiz (who presented at the MEMS Business Forum, and who’s actually a pretty entertaining presenter), RF performance has been degrading from generation to generation as the number of bands has increased. From 4G on, he points to the need for better antennas, power amps, and filtering – as well as MIMO technology – in order to improve things.

And tunable RF circuits using MEMS-based variable capacitors seems to be what can get us there. He runs a lab that tests out the various solutions available, and he says that the MEMS versions are amazingly linear, with low loss, high quality, and other favorable characteristics. He paints them as 5 – 10 times better than silicon-on-insulator (SOI), silicon-on-sapphire (SOS), or barium strontium tinanate (BST) tuners.

He sees tunable antennas being common in 2013 and 2014, followed by tunable power amps, then notch filters, and then bandpass filters (if there are any). The two MEMS players that lead in the cellphone space and that presumably will be facilitating this change are WiSpry and Cavendish Kinetics.

But he also sees needs in base stations, instrumentation, defense, satellite communications, and automatic test equipment. And he waxed effusive over the performance of Omron’s MEMS switch, which dominates in this market. He simply calls it “amazing,” the “best RF MEMS switch in the world.”

The one gotcha for all of this, however, is cost. It must be low – 20 – 25 cents for a variable capacitor in a phone. He points to integrated CMOS and RF MEMS as the way to make this happen. Cavendish Kinetics’ technology is CMOS compatible; WiSpry includes CMOS on their chips. So now we just have to watch to see whether the prices get to where they need to be.

Leave a Reply

featured blogs
May 20, 2019
At the 2019 International Symposium of Physical Design, the conference honored Alberto Sangiovanni-Vincentelli with a lifetime achievement award. Alberto was one of the cofounders of SDA Systems, the... [[ Click on the title to access the full blog on the Cadence Community s...
May 17, 2019
The Design Automation Conference (DAC) is the premier conference for automated electronics design and verification technology. For 2019, DAC returns to sunny Las Vegas, Nevada at the Las Vegas Convention Center from June 2-5, 2019. We'€™ve packed each day full of exciting ...
May 17, 2019
In the days of old we looked into the “green” for guidance on how much further down into the world of miniaturization we could go. What is the green you ask? I am talking about the substrate that has served us all well for many years; the PCB. We are at a crossroa...
Jan 25, 2019
Let'€™s face it: We'€™re addicted to SRAM. It'€™s big, it'€™s power-hungry, but it'€™s fast. And no matter how much we complain about it, we still use it. Because we don'€™t have anything better in the mainstream yet. We'€™ve looked at attempts to improve conven...