The number of circuit poles characterizes the shape of a low pass filter’s attenuation curve beyond their cutoff. One can estimate that filter attenuation beyond cutoff is 20 dB per decade change in frequency for each circuit pole. For example, single pole LP filters have an attenuation curve slope of only 20 dB per decade change in frequency, whereas a 7-pole LP Filter has a 140 dB per decade slope.
Dataforth SCMs employ multiple pole LP filters; 5-poles to 7-poles depending upon the specific application, Moreover, all Dataforth’s isolated SCMs have filtering on both the field side and output side with antialiasing characteristics on the field side.
For example, on the first page of the following data sheet you see a typical block diagram with the depiction of low pass filters on both the field-side and system-side of the circuit. On the second page of this data sheet you can see how we state bandwidth, attenuation per decade (NMR = Normal Mode Rejection) and step response time (time it takes to output to 90% of a fast change on the input).Dataforth Strain Gage Input Conditioner DSCA38
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