1 / 43

Electronics and Noise, Ch. 14 and 16, Senturia

Electronics and Noise, Ch. 14 and 16, Senturia. What determines the performance of a sensor? Minimum Detectable Signal? (What does this mean?) Precision? Accuracy? Frequency Response? Dynamic Range? (What does this mean?). Look at the ADXL 204. Sensitivity What is the significance?

otis
Download Presentation

Electronics and Noise, Ch. 14 and 16, Senturia

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Electronics and Noise, Ch. 14 and 16, Senturia • What determines the performance of a sensor? • Minimum Detectable Signal? (What does this mean?) • Precision? • Accuracy? • Frequency Response? • Dynamic Range? (What does this mean?)

  2. Look at the ADXL 204 • Sensitivity • What is the significance? • Noise Specs? • What is the signficance? • Anything on accuracy or precision? • ?

  3. Plan • Start with elecronics – review op-amp circuits • Talk about noise in general • Do some examples using specs for particular op-amps.

  4. Slew-Rate • Another limitation, in addition to all the others, that comes from properties of the op-amp circuit: • Slew-Rate: • The rate at which the output voltage can change • Typically measured in V/ms (at the output) • It is another spec. for op-amps • Typically 0.5-1,000 V/ms • Sometimes this needs to be large for driving something like an electrostatic actuator.

  5. Noise, Ch. 16, Senturia • Noise often limits performance of MEMS sensors and other devices (oscillators, filters, for example). • What we often think of as noise can be divided into 2 (or more) parts. • 1. Interference. • 2. Random noise. • 3. Drift, aging effects… (random noise??)

  6. Interference • Definintion: Unwanted sensitivity to external or internal disturbances. • Electrical, thermal, mechanical, optical… • Examples. • Electrical: Capacitive coupling to 60 Hz, radio waves, driving voltage to output … • Mechanical: Sensitivity to vibration… • Optical: Sensitivity to ambient light. • Thermal: Sensitivity to temperature (very common!) • System design critical (Senturia has examples) • References: Keithley, Low-Level measurements + others.

  7. Random Noise • Thermal noise. • Dissipative processes result in fluctuations. • Energy storage elements have a non-zero fluctuating amount of energy stored. • Shot noise. • Current consists of discrete particles. • Flicker noise (1/f noise). • Mostly capture and release of carriers from traps in electrical circuits. Many physical mechanisms, generally.

  8. Thermal Noise • Statistical mechanics -> average energy of a particle = 3/2 kBT. (1/2 KBT for each degree of freedom (x, y, z)) • Mass with 1 degree of freedom -> ½ kBT <-> inductor! • Inductor has on average ½ kBT of energy. • The capacitor is also an energy storage element with one degree of freedom. If connected to its environment with a resistor (or almost anything else) it has an average stored energy of ½ kBT! This does not depend on the size of the resistor or capacitor! • Spring (capacitor) also has ½ kBT. • This is characteristic of thermal noise.

  9. 4kT=4.1x10-21 at 300 K

More Related