I am looking to use a band pass filter in an EMG circuit design using the differential signals you receive from an op amp (differential/instrumentation). I have been looking for what is the proper way to do filtering and have not found a high-pass or bandpass filter explanation like in the article below yet. I realize there is some nuance to differential vs single pole filters, as talked about in TI's article here, like having the "differential capacitor" be 10 times the value of the "common mode capacitors."
Please especially note Figure 4:
It is very helpful and shows what I would use for a low pass filter on the two lines, equation 3 calculates the cutoff frequency. I have not seen an equivalent article for the high pass filter and so I thought I would ask here to see if its as simple as I think it is or there are other things to think about.
My main question are
- whether or not the high pass filter would be similar to the circuit in Figure 4 except the resistors and capacitors are switched, as they are for single pole; and
- whether for a band pass, you would just utilize the HPF and LPF in succession if that is the case.
I'll try to make a schematic later today when I have time if it's not clear and I can find a good tool to use.