B8378 - SENSORI ELETTRONICI INTELLIGENTI LM

Learning outcomes

The goal of this section is to provide to students the fundamental know-how regarding sensor and transducer systems design. The course scheme avoids to tackle the subject as a collection of different cases of sensing systems. Instead, it is structured to underline the common backgrounds of the sensing paradigms such as noise floor and sensing limits. More specifically, a generic sensor acquisition chain will be analyzed from the sensitivity and resolution point of view with respect to the background and devise noises. The learning outcomes are 1) understanding basic physical aspects of sensing and noise principles 2) analysis and design of electronic interfaces for sensors. Lectures are often based on a bottom-up approach to better understand principles from examples.

Course contents

• Introduzion of the course, example of research

• Sensors as a black-box. Concept of sensitivity, and relative sensitivity at first order approximation.

• Measurements, precision, accuracy and resolution. Full scale and dynamic range.

• Recall of stocastic signals. Rms values and mean square values, standard deviations. Power spectral density. Correlation, autocorrelation and cross-correlation.

• Suprimposition of noise powers in uncorrelated signals.

• The origin of noise. Brownian noise. The example of pressure sensor.

• Noise in electronic components. Thermal noise and its derivation.

• Possonian processes. Shot noise and related derivation.

• Concept of input-referred noise. Input referred noise in BJT and MOS devices.

• The flicker noise and its derivation. Physical origin of flicker noise.

• Equivalent noise bandwidth. Signal-to-noise-ratio (SNR)

• White and pink noises.

• Acquisition sensor chain. Probability errors and equivalent number of levels.

• Noise in OPAMPs

• Resistive sensors interfaces. Wheatstone bridge and its sensitivity.

• Microcontroller sensing of resistors and capacitances. Ratioed measurements.

• Strain-gauges. RTDs e PRTs.

• Thermistors, NTC e PTC. Magnetic sensors.

• Capacitive sensors. Capacitance matrix. Kelvin guard ring.

• Charge amplifier. Differential capacitive sensing. Capacitive accelerometers.

• Noise in charge amplifiers. Correlated double sampling (CDS).

• Open and closed loop sensing. Oversampling converters. Sigma-Delta converters. Decimators.

• Lock-in e chopper sensing. Complex impedance measurements by lock-in sensing.

• Introduction to optical sensors. The photodiode. Charge and voltage photodiode readout in storage mode.

• Sensor networks.

• Array of optical sensors. Passive pixel CMOS sensors (PPS) and active pixel (APS) sensors. APS with correlated doble sampling. CCD principles.

• Teoria del colore and color filtering.

 

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