RF MEMS The solution to power hungry smart phones

What are MEMS?Micro(small)

Electro(electric components/functionality)

Mechanical(mechanical components/functionality)

Systems(integrated, system-like functionality)

http://eed.gsfc.nasa.gov/562/SA_MEMs.htm

http://www.memx.com/

http://www.memx.com/

http://www.forbes.com/2008/04/22/mems-apple-nintendo_leadership_clayton_in_jw_0421claytonchristensen_inl_slide.html

Where do you find MEMs?Printers

*High DPI inkjets

Projectors*Micro-Mirrors from Texas Instruments

Cell Phones*Knowles Microphones used in most new cell

phones

Automobiles

LIMITATIONS OF EXISTING :

Photovoltaic cells and wind power harvesting have several technical barriers.

In solar cells, the inherent physical limits, the black body energy conversion loss, optical loss, and internal resistance prevent their efficiency from reaching >20%

Why MEMS…?Small

*Typically .1-100um feature size

Human Hair thickness ~ 50um

http://www.vendian.org/envelope/dir2/scaling_construct.html http://singularityhub.com/wp-content/uploads/2008/08/red-blood-cells.bmp

Red Blood Cells ~ 10um

Low cost, High yield*Use existing IC fabrication technology

*Made primarily on Silicon Wafers

Why MEMS…?Favorable scaling for a lot of applications

*Flow-rate sensors*Electrostatics*Magnetism*Many others

Not all applications*Solar Power*Turbulent Boundary Energy Harvesting

Where it Began…? 1979 - First recorded use of MEMs in automobiles

Federal emission standards required monitoring the air-to-fuel ratio of the engine

Density of air value was needed

Many different sensor technologies were introduced to solve this problem

MAP (manifold absolute pressure) and MAT (manifold air temperature) sensors were developed using MEMS

Silicon based MEMS sensors became the device of choice due to low cost and high yield

MAP Sensor

Who Developed It…?Two groups

*Delco Electronics Group(General Motors)*Used piezo resistive sensing

Ford*Used capacitive sensing

Typical Applications

* Accelerometers* Microphones* RF-MEMS Switches* Bridge to Nanotechnology* Mobile Communications

RF-MEMS SwitchesTypes :-

* Capacitive shunt switch: 1.OFF state with capacitive coupling

2.Isolation dependent on capacitive ratio between ON and OFF state

3.Longer contact lifetime

* Direct Contact Series Switch:

1.ON state with metal-to-metal ohmic contact2. Insertion loss dependent on the contact resistance3. Broad frequency coverage

Mobile CommunicationsFully Integrated Tunable RF * If you put your finger on an RF MEMS antenna it can

automatically re-tune itself so that no calls are dropped. *Furthermore, RF MEMS can react to atmospheric

conditions and re-tune your phone’s radio to improve 3G and LTE data throughout.

* Most importantly, though, RF MEMS paves the way towards devices with just a single antenna and transceiver.

Number of radios in smart phones:

*GSM

*3G

*CDMA, W-CDMA

*Bluetooth, Wi-Fi

* New approach to ohmic switching.

* It can be integrated with capacitors using wafer-level thin-film packaging.

* Multiband (800-to-2200-MHz), low-loss (0.3-dB) chips measure just 3.5 x 4.2 x 1.1 mm.

SPECIFICATIONS

STATISTICS….

Advantages : *cost about 2 to 2.5 cents/switch throw—in SPST

and SPDT configurations*High precision, High reliability, Linearity*Simplicity of principle*Compatible with conventional IC’s*Low weight*60% reduction in board space.Limitations: *Slower switching speed *Potential lifetime limitations *Packaging

Advantages & Limitations :

CONCLUSION MEMS technology provides powerful tools to the RF technology. Replace conventional solid state circuit devices on size.

Overall MEMS field is not much more than 10 years old, and the RF MEMS field has really been shaped within the past 5-6 years.

The future should be bright and unlimited

By Sai Chand Surya

Thank U.........!

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