Teledyne 3290 - OEM percent oxygen analyzer - Manual (Page 23)

Percent Oxygen Analyzer Operational Theory
Teledyne Analytical Instruments 13
Figure 2-3: Block Diagram of the Signal Processing Electronics
In the presence of oxygen the cell generates a current. A current to
voltage amplifier (I–E AMPL) converts this current to a voltage.
The second stage amplifier (TEMP COMP) supplies temperature
compensation for the oxygen sensor output. The temperature
compensation amplifier incorporates a thermistor (THERM) that is
physically located in the cell block for the typical oxygen sensor. The
thermistor is a temperature dependent resistance that changes the gain of
the amplifier in proportion to the temperature changes in the block. This
change is inversely proportional to the change in the cell output due to
the temperature changes. As a result there is negligible net change in the
signal due to temperature changes once the sensor comes to equilibrium.
See Specifications in the Appendix.
The output from the temperature compensation amplifier is sent to
an analog to digital converter (ADC), and the resulting digital
concentration signal is sent to the micro-controller.