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ADS8598S: Is ads8598s bandwidth limited by internal LPF?

user1368590
Prodigy 10 points
Part Number: ADS8598S

I thought I could fully digitize a 20kHz signal using the ADS8598S with 200ksps. But what I am confused is that the ads8598s's builtin LPF has –3-dB cutoff frequency at 16kHz

Why does the ADS8598S have an antialiasing filter with such a low cutoff frequency compared to the Nyquist frequency?

  • 0
    TI__Mastermind 24388 points

    Dear User,

    You are correct.  This filter will limit your bandwidth.  The reason this filter is included is to improve noise performance (i.e. the 1Mohm input resistance generates thermal noise that can be an issue in many applications).  Most of the similar ADC with an integrated analog front end that uses 1Mohm input resistors has a similar restriction.  The one exception to this is the ADS8686.  I am sorry if this filter limits the usage of this device in your application, but the filter cannot be bypassed. 

    Thanks,