Abstract
This paper evaluates the performance of direct interface circuits (DIC), where the sensor is directly connected to a microcontroller, when a resistive sensor subjected to dynamic changes is measured. The theoretical analysis provides guidelines for the selection of the components taking into account both the desired resolution and the bandwidth of the input signal. Such an analysis reveals that there is a trade-off between the sampling frequency and the resolution of the measurement, and this depends on the selected value of the capacitor that forms the RC circuit together with the sensor resistance. This performance is then experimentally proved with a DIC measuring a magnetoresistive sensor exposed to a magnetic field of different frequencies, amplitudes, and waveforms. A sinusoidal magnetic field up to 1 kHz can be monitored with a resolution of eight bits and a sampling frequency of around 10 kSa/s. If a higher resolution is desired, the sampling frequency has to be lower, thus limiting the bandwidth of the dynamic signal under measurement. The DIC is also applied to measure an electrocardiogram-type signal and its QRS complex is well identified, which enables the estimation, for instance, of the heart rate.
Highlights
IntroductionIn the society of the 21st century, almost everything (e.g., home appliances, mobile phones, cars, buildings, and cities) is becoming “smart” thanks to the proliferation of information and communication technology and the deployment of technologies, such as wireless sensor networks and the Internet of things
In the society of the 21st century, almost everything is becoming “smart” thanks to the proliferation of information and communication technology and the deployment of technologies, such as wireless sensor networks and the Internet of things
According to these experimental results, we can confirm that the sensor equivalent resistance linearly changes with the magnetic field applied
Summary
In the society of the 21st century, almost everything (e.g., home appliances, mobile phones, cars, buildings, and cities) is becoming “smart” thanks to the proliferation of information and communication technology and the deployment of technologies, such as wireless sensor networks and the Internet of things. Sensors are electronic devices that provide an output signal in the electrical domain (e.g., resistance, capacitance, voltage, or current) with information about the measurand Such an electrical signal is generally of low amplitude and carries some noise and, an electronic interface is required between the sensor and the processing digital system so as to correctly extract the information of interest. The sensor output signal is first processed in the analog domain by a signal conditioning circuit that generally relies
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