Monday, March 14, 2011
Arbitrary Waveform Generator Makes MEMS Waveforms
MEMS, microelectromechanical systems, require complex driving waveforms to achieve optimal performance and device lifetime. Often many of the same devices are needed for a given application. Cost considerations usually require these many devices to be operated open loop. If the driving waveform to these many devices can be optimized, both performance and lifetime for the MEMS devices can be dramatically improved. BNC’s arbitrary waveform generator, Model 645, has been an effective tool in determining what that waveform should be.
For example, MEMS switch lifetimes can be maximized by careful selection of the driving waveform. It has been shown that the number of reliable switch operations on a particular RF MEMS switch can range from 10*4 to 10*8 depending on the actuator drive voltage level. It has also been shown that tailoring of the waveform shape can also increase the switching speed by reducing contact bounce. An example of such a waveform is a pulse to activate the switch, a period of no signal and then a hold pulse at a level much lower than the activation pulse. An ARB is used to adjust the timing and amplitude of each phase of the drive signal. With an ARB one
can even adjust the shape of the driving pulses from step function to bandwidth-limited drives.
What was particularly useful was the Model 645’s ability to store complete sets of the 14-bit, 256K waveform so that one could tweak, store and compare with other waveforms. The Model 645 offers 14-bit resolution and a 125 MSa/s sampling rate, giving this MEMS application the time and amplitude control it needed. More details on the complete benchtop line of test equipment is available at www.berkeleynucleonics.com or 800-234-7858.