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Amplifier drives MEMS devices

Posted: 06 May 2005 ?? ?Print Version ?Bookmark and Share

Keywords:mems? micro electro-mechanical system? tegam? driver amplifier? model 2375?

The advent of MEMS (micro electro-mechanical systems) has given rise to specialized instrumentation for these devices. In response to the proliferation of MEMS, instrumentation house Tegam Inc. is now offering a four-channel MEMS engine driver amplifier priced at about $6,500.

The Model 2375 was co-developed with Sandia National Laboratories for the purpose of driving electrostatic comb-type rotating MEMS microengines. The 2375 accepts low-level inputs and amplifies them. Each channel's internal amplifier can also be bypassed.

In addition to driving MEMS microengines, the 2375 can be used anywhere precise signal amplification of uni-polar or DC-biased AC waveforms is needed.

In use, the four-channel amplifier's individual channels are rated for 20mA of continuous current (into a 0.2? output impedance), over a -7V to 150V range, slewing at better than 5V/?s. Each channel can be set for gain and offset using internal controls.

The 2375 can also drive capacitive loads up to 200pF, while maintaining a full power bandwidth, which extends from Dc to more than 5kHz (flat to within -0.1dB). Finally, the outputs are short-circuit protected by current limiting circuits.

Each channel also has an independent voltage monitor output. That's for applications that require a low-level representation of the output signal in a closed-loop system. The buffers produce a reduction of 100:1 of the output voltage for measurement devices with a 1 M? (or higher) input impedance. Monitor outputs, through BNC connectors, are also provided. These can be used to connect to an oscilloscope, an ADC card, or other monitoring device of your choice.

A complete system

Tegam also offers a Model 9070 MEMS Engine Driver System that uses one of the 2375 driver amps. The 9070 is a stable signal source designed to drive comb-type MEMS microengines (it's also a direct replacement for Pragmatic Instruments' 9014 MEMS engine driver system. The 9070 is priced starting under about $15,000.

A typical 9070 system consists of Sandia National Laboratory's Super ?Driver software, two waveform generators, and one 2375 amplifier. The channels can be operated in pairs using the 2375's built-in splitter, or operated individually. The waveform generator can be programmed to output ideal MEMS drive signals, sine waves, square waves, or any arbitrary waveshape. Signal amplitude is set at the waveform generator.

All four channels are also remotely programmable using IEEE-488.2/GPIB. Waveforms and drive parameters for each channel can be created and downloaded using the Super ?Driver software.

- Alex Mendelsohn

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