Weakly inverted MOSFETs and their applications

The relevant properties of the weakly inverted MOSFETS are examined for high impedance sensor applications. The characteristics of these devices are exponential and their transconductance approaches that of bipolar transistors through a factor n which is a useful characteristic of these devices. The high frequency noise spectrum in these devices is found to be white and inversely proportional to the drain current. The high frequency noise spectrum is related to n and is identified to be thermal noise. The 1/f noise corner frequencies in these devices are found to be lower than in the strongly inverted region. These properties make the weakly inverted MOSFETS useful as amplifiers in low power, low frequency and high impedance sensor applications.