Integrating the data converter with a MEMS sensor is the way ahead, writes David Dunn, a field applications engineer at Analog Devices
Design engineers are increasingly combining the converter core and sensor IC as an integrated unit to optimise sensor performance. The “sensor-converter” is viewed as a single unit for analogue signal acquisition and digital post processing requirements.
MEMS (micro-electromechanical system) inertial sensors, typically accelerometers and gyroscopes, are combined with data converters to sense inertial and rotational motion.
This can create a number of design advantages. The converter can use internal calibration and linearisation routines to process sensor outputs.
Sensor gain and offset can be corrected by the converter and on-chip sensor excitation signals can be created.
Digitally managed programmable gain amplifiers can be used to “optimise” the converter to a particular sensor reading and then reconfigure to read a different signal from the same sensor.
Thermal errors can be accounted for and removed by including temperature monitoring capability in the converter and adjusting the converter output based on the temperature. Many new applications of this combination of MEMS sensors and converters are yet to be discovered.
Moreover, given that the sensor signal is typically small enough to be corrupted by noise, the ability to co-locate the converter and sensor means that the signal now travels microns not feet, making sensor calibration easier and more reliable.
As system design becomes more heavily dependent on integrated sensors, the converter needs to be even more sophisticated and functional. As the converter’s importance in the overall system grows, a greater emphasis is placed on designers to meet system redundancy and functional safety concerns requiring deep converter understanding to ensure that these issues are appropriately managed.
Because of the crucial role they play in faithfully reproducing real-world phenomena, today’s data converters are evolving to achieve the most lifelike user experiences possible.
Continued integration with MEMS components will yield better performance and, in many cases, alleviate issues associated with system-level design partitioning, while simultaneously reducing design complexity.
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