Question

My real-world signal has frequency components that extend into the MHz range, however I am most interested in a signal that occurs near 100 kHz. Also, my AtoD has a max sampling rate of 1 MHz. What type of analog filter will I apply to this signal to avoid aliasing? Can you recommend a particular filter design, knowing that I am more interested in spectral content than a time-domain analysis?

Answer 1

As you have mentioned that the frequency of interest is about 100kHz, So you can use low pass filter with a cut-off frequency of 10% more than the frequency of interest.

Cut-off frequency

As you have mentioned that the sampling rate of your ADC is about 1MHz Since, This sampling rate is satisfying the sampling theorem which states that the sampling frequency should be greater than the twice of the maximum frequency present in the message signal (1MHz>>2-*110kHz) So, you will have no issues with that.

You just need to put a Low Pass Filter in between your signal source and ADC.

You can easily build such low pass filter with resistor and capacitors.

For R=100kOhm

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