Transversal noise current in split-drain transistors

An excess noise current in CMOS MAGFET split drain transistor is investigated and a new noise model is proposed. It is based on the existence of the transversal noise current that stems from the inversion charge from the MOS transistor channel. This noise current along with the one predicted by the classical MOS transistor produces the total split-drain noise current. This noise current impacts the signal-to-noise ratio and minimum detectable magnetic field, parameters of interest in CMOS-based magnetic sensors. Noise measurement were applied to verify the combined effect of this noise currents. Essentially, it has been observed that a negative correlation between drain currents takes place in split-drain transistor operating in saturation region. Noise voltage power spectral density (Voltage-PSD) measurements were made for split-drain MAGFETs manufactured in 0.8mum, 0.6mum and 0.35mum CMOS with geometric aspect ratio of 10mum/10mum, 24mum/30mum and 10mum/10mum, respectively