N o i s e
This page describes the Two-Dimensional Position Detecting system that won the First Prize in the "Conceptual Category".

 

 

Brownian Noise

The initiative scientist, Robert Brown, first observed the random movements of pollens in 17th centuary. The randome motion was caused by irregular collisions of water molecules. This "Brownian motion" was first investigated analytically by Louis Bachelier in his doctoral dissertation Theorie de la speculation, a mathematical model of the stock market. Later Albert Einstein also studied this movement and made a supportive conclusion that the random motion of pollen was caused by random water molecules collisions due to thermal motion. Similar to "white noise", the brownian noise is independent of the past. Therefore, considering any change from a certain time to another is random and normally distributed, Brownian noise is the integral of white noise.

In this project, this Brownian noise mostly comes from mechanical sources, MEMS accelerometer. Especially the air damping between proof mass and stagnant electrode causes 10ug/sqrt(Hz). Other Brownian noise sources are ignored because of its little contribution.

Additional References:

  1. Paul Burke astronomy.swin.edu.au
  2. Terry Ritter, P.E., Ritter Software Engineering

     

Amplifier Noise

In this project, this amplifier noise mostly comes from the physical noise sources of analog circuits. For example, first, resistors and MOSFET channels contribute to thermal noise owing to the random collision of the electrons with vibrating atoms. Second, the unexpected defects caused by the fabrication process contribute as a source of flicker noise. Third, the unstable power supply of the op-amp becomes a part of amplifier noise. Especially this noise depends on the charge sharing determined by external capacitor values and approximately results in 0.7ug/sqrt(Hz).

 

Additional References:

  1. C.R. MacCluer --- Professional Homepage Michigan State University
  2. Tube CAD Journal, April 1999, page2
  3. Tube CAD Journal, April 1999, page3
 

KT/C Noise

 In this project, this KT/q noise mostly comes from thermal noise sources of analog circuits during the sampling. Especially the uncertainty of the time varying operating point due to thermal noisy components results in 0.3ug/sqrt(Hz).

Additional References:

  1. Paul Burke astronomy.swin.edu.au
  2. Terry Ritter, P.E., Ritter Software Engineering
 

* If you have any questions, please don’t hesitate to contact hanseup@engin.umich.edu.