A pressure transmitter with first and second absolute pressure sensors
receives process pressures from corresponding first and second process
inlets. A transmitter circuit coupled to the first and second absolute
pressure sensors generates a differential pressure type output. A third
absolute pressure sensor coupled to the transmitter circuit receives
atmospheric pressure from a third inlet. The transmitter circuit generates
a second type of transmitter output that can be a gage or absolute
pressure type. Single crystal. sapphire pressure sensors are preferred to
provide enough accuracy for measuring accurately over 200:1 pressure
range.