Pseudodifferential Multichannel Bridge Digitizer and Digital Cold Junction Compensation
Apr 29th 2010
This circuit enables pseudodifferential measurements of several bridge transducers and absolute temperature measurement. Consecutive readings are performed on each side of the bridge by selecting the appropriate channel on the LTC2428. Each output is digitized and the results digitally subtracted to obtain the pseudodifferential result. Several bridge transducers may be digitized in this manner. In order to measure absolute temperature with a thermocouple, cold junction compensation must be performed. Channel 6 measures the output of the thermocouple while channel 7 measures the output of the cold junction sensor (diode, thermistor, etc.). This enables digital cold junction compensation of the thermocouple output. The temperature measurement may then be used to compensate the temperature effects of the bridge transducers.
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