Patent ID: 6910804

Claim:
A system for improving noise immunity for a resistive temperature device (RTD) module, comprising: an RTD system which includes a plurality of resistive temperature devices (RTDs) and an RTD bank assembly to which the RTDs are connected, the RTD bank assembly including a current source applied successively to the RTDs connected thereto, a switching means for switching the current source successively between the plurality of RTDs in a known sequence, and a measurement assembly for measuring the voltage drop across each RTD when the current source is connected thereto, the RTD system further including a calculation circuit for calculating the resistance of the RTD from the current applied thereto and the voltage drop thereacross; a plurality of low pass filters associated, respectively, with the plurality of RTDs, wherein when the voltage across an RTD is applied to its associated low pass filter, the low pass filter charges over time, wherein the voltage on the low pass filter is not used in calculating resistance of an RTD until the low pass filter associated with the RTD reaches a preselected level of charge wherein the plurality of low pass filters are charged in turn and the voltage thereon sampled; and a system for successively precharging low pass filters associated, respectively, with successive RTDs prior to sampling thereof, so that delay in sampling is significantly reduced.