Noise due to Brownian motion in ultrasensitive solid-state pressure sensors

Noise due to Brownian motion of diaphragm in ultrasensitive solid-state capacitive and piezoresistive pressure sensors operating at sub-millimeters of mercury pressures in a gaseous ambient is considered. The statistical properties and spectral characteristics of the noise are obtained as functions of the diaphragm dimensions, temperature, and applied pressure. The results show that the Brownian equivalent pressure noise is substantially less than has been previously reported and is well below 1µmHg for most practical cases of interest. Thus it is not a limiting factor in setting device performance when compared to circuit noise sources.