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MEMS and Sensors

Application Notes

Circuits from the Lab

New Product Briefs

Technical Articles

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MEMS and Sensors Home

Application Notes

AN-1295: Mechanical Design Tips for ADIS16375, ADIS16480, ADIS16485, and ADIS16488

Packages for the ADIS16375, ADIS16480, ADIS16485, and ADIS16488 include four 2.4-mm mounting holes, an aluminum housing, and a 2-row, 24-pin, 1-mm pitch electrical interface connector. This 4-page Application Note provides tips for system-level installation.

AN-1266: Autonomous Shock Event Monitoring with the ADXL375

This 6-page Application Note describes a technique for autonomously detecting and capturing shock events using a low power, high-g, 3-axis digital MEMS accelerometer with minimal intervention from the host processor. The accelerometer can be programmed to monitor single or double (primary and secondary) shocks along any combination of X, Y, and/or Z axes. In addition, the entire shock profile can be captured for further analysis using an integrated 32 sample memory.

AN-1181: Using a MEMS Microphone in a 2-Wire Microphone Circuit

MEMS microphones are being used to replace electret condenser microphones (ECMs) in audio circuits. These two types of microphones perform the same function, but the connection between the microphone and the rest of the system is different for ECMs and MEMS microphones. This 2-page Application Note explains those differences and provides design details for a simple MEMS microphone based replacement circuit.

AN-1165: Op Amps for MEMS Microphone Preamp Circuits

A microphone preamp circuit amplifies a microphone’s output signal to match the input level of the following device. Matching the peaks of the microphone’s signal level to the full-scale input voltage of an ADC makes maximum use of the ADC’s dynamic range and reduces the noise that subsequent processing may add to the signal. The MEMS microphone has a single-ended output, so a single op amp stage can be used as a preamp to add gain to the microphone signal or to buffer the output. This Application Note covers some of the key op amp specifications to consider for a preamp design, shows a few basic circuits, and provides a table of Analog Devices op amps that are appropriate for a preamp design. The ADMP504 MEMS analog microphone with 65 dB SNR is used as an example to describe different design choices.

AN-1157: Tuning the Extended Kalman Filter in the ADIS16480

The ADIS16480 MEMS inertial measurement unit (IMU) includes a 3-axis accelerometer, a 3-axis gyroscope, a 3-axis magnetometer, and a barometer. It also includes an extended Kalman filter (EKF) that computes dynamic orientation angles. The EKF estimates the orientation angles using a combination of gyroscope, accelerometer, and magnetometer contributions, with real-time filter weighting factors determined by covariance terms representing the level of uncertainty assigned to each sensor. Optimal performance comes from selecting appropriate covariance values for the sensors, given the application environment. This 8-page Application Note offers analytical tools for simplifying this process.

Circuits from the Lab

CN0303: MEMS-Based Vibration Analyzer with Frequency Response Compensation

This circuit offers a high linearity, low noise, wide-bandwidth vibration sensing solution that is ideal for applications, such as bearing analysis, engine monitoring, and shock detection, that require high dynamic range (±70 g to ±500 g) and flat frequency response to 22 kHz.

CN0284: High-Performance, Low-Noise Studio Microphone with MEMS Microphones, Analog Beamforming, and Power Management

This professional-grade studio or live-performance microphone uses up to 32 analog MEMS microphones connected to op amps and a difference amplifier. Designed for low noise, its output is linear for acoustic inputs up to 131 dB SPL. Powered from a single 9-V battery, the ±9-V and 1.8-V power rails are generated from two voltage regulators. The ADMP411, which consists of a MEMS microphone element and an impedance-matching amplifier, has a frequency response that is flat to 28 Hz, making it ideal for full-bandwidth, wide dynamic range audio capture.

New Product Briefs

March 2014

Tactical-grade Inertial Sensor features ten degrees of freedom

adis16488aThe ADIS16488A complete “10-degrees-of-freedom” inertial sensing system combines a 3-axis gyroscope—with ±450°/s dynamic range; a 3-axis accelerometer—with ±18-g range; a 3-axis magnetometer—with ±2.5-gauss range; and a barometer—with 300‑mbar to 1100-mbar range; plus a local temperature sensor and a 12-bit ADC. The device is fully calibrated for sensitivity, bias, axial alignment, and linear acceleration over the –40°C to +85°C temperature range. Functionally complete, it includes programmable self-test, power management, and alarms. All data and commands are communicated via an SPI-compatible serial interface. Operating on a single 3.0-V to 3.6-V supply, the ADIS16488A consumes 245 mA in normal mode, 12.2 mA in sleep mode, and 45 µA in power-down mode. Available in a 47-mm × 44-mm × 14-mm module with a 24-pin connector, it is specified from –40°C to +85°C and priced at $1190.00 in 1000s.

Technical Articles

Bob Scannell, Wireless Vibration Sensors Enable Continuous And Reliable Process Monitoring, Electronic Design, 2014-02-25

Jerad Lewis and Brian Moss, MEMS Microphones, the Future for Hearing Aids, Analog Dialogue, 2013-11-01

Ben Wang, Reduced Integration Time Improves Accuracy in Dead Reckoning Navigation Systems, Analog Dialogue, 2013-07-02

Bob Scannell, Micro Motion, Electronic Specifier, 2013-07-01

Jerad Lewis, Analog and digital MEMS microphone design considerations, EE Times, 2013-03-27

Webinars and Tutorials

What is a "Wide Dynamic Range" Microphone and why does it matter to my design? - MEMS microphones with the capability to capture very high sound pressure acoustic waves (loud noises) with high fidelity hold the potential to improve user experience in audio capture and to make acoustic detection viable for a range of applications that might have previously been unsuitable for such methods. We'll discuss design considerations for these microphones and applications that might benefit from such high performance.

High-Performance MEMS; What does that mean? – Learn the most common "high-performance metrics" that are associated with gyroscope/IMU applications, and gain insight into their characterization and performance impact in real-world applications. Topics covered in this webcast will also be useful for applications that use accelerometers.

Healthcare Webcast: MEMS Inertial Sensors in Healthcare Designs - In this webcast you will learn the basics on MEMS motion sensing including architectures and technology including accelerometers, gyroscopes, and IMUs. Applications explored include precise positioning/tracking of healthcare scanning equipment, surgical tool guidance, balance and control of prosthetics, and motion sensing.

Using MEMS Sensors for Industrial Platform Stabilization Systems - MEMS accelerometers and gyroscopes are ideal feedback sensing elements for many types of platform control and stabilization systems. This webcast will discuss typical performance requirements to consider when developing a MEMS-based stabilization system, along with insights on component selection and enabling quick, inexpensive, system-level integration of these functions.

 

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