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Comparator.jar
Comparator Hysteresis Network
TheComparator Network Search Tool is used to find a set of resistor values inan inverting comparator circuit that provides the required switching threshold voltage andhysteresis. The reverse can also be performed, finding threshold and hysteresis voltages based onknown resistor values. The application can be started using Java Web Start by clicking the Launchbutton below. Alternatively, a executable Jar file can be downloadedusing the link above.
Inverting Comparator Circuit
The inverting comparator circuit analysed by the search tool is shown in the left-hand figurebelow. The feedback resistor provides hysteresis to the switching threshold voltages. The right-handimage below shows how the output voltage changes when the input crosses the switching thresholds.
 Inverting comparator circuit |  Input and output voltages of inverting comparator circuit |
The image below shows the importance of using a comparator circuit with some input hysteresis.The example is cleaning up a noisy waveform into a binary output signal. The input voltage waveformis shown in the lower blue waveform. The output of a simple comparator without any thresholdhysteresis is shown in the top red waveform. The noise means the input crosses the centre thresholdmany times, so the output switches accordingly.
The middle green waveform shows the result of using threshold hysteresis. When a switchingthreshold is crossed, the output changes and the threshold changes as well. This means is it lesslikely that noise will cause the output to switch again.
Input hysteresis can help clean up noisy data
The two equations below can be used to calculate the switching thresholds based on the comparatorcircuit resistor values.
