Help needed with Low/High cutoff filter modification of RF Doppler circuit for higher speed reading

Discussion in 'Wireless & RF Design' started by fe7565, Jul 6, 2019.

  1. fe7565

    Thread Starter New Member

    Aug 13, 2016
    3
    0
    24ghz doppler radar-project.jpg I am looking at the attached circuit that uses a CDM-234 Doppler sensor with a very low voltage output. The attached circuit is setup to read a bandwidth of around between 0-115 FPS speed and I want it to read between 300-1,300 FPS. I am hoping to modify the circuit by changing the values of resistors and capacitors for Opamp 1 and Opamp 2 (see below).

    Current High cutoff is about 3 hz and the Low cutoff is about 999 hz. The new High Cutoff should be 15 Khz and Low cutoff 65 khz.

    High cutoff opamp1: C18=10uF R17= 4.7Kohm => new values C18=1nF R17=10Kohm
    Low cutoff opamp1: C23=270pF R20=590Kohm => new values C23=100pf R20=25Kohm or C23=10pf R20=250Kohm or C23=2.5pF R20=1Mohm

    High cutoff opamp2: C19=10uF R18= 4.7Kohm => new values C19=1nF R18=10Kohm
    Low cutoff opamp1: C24=270pF R21=590Kohm => new values C24=100pf R21=25Kohm or C24=10pf R21=250Kohm or C24=2.5pF R21=1Mohm


    Appreciate any help!
     
    Last edited: Jul 6, 2019
  2. fe7565

    Thread Starter New Member

    Aug 13, 2016
    3
    0
    Second set of Opamp number should be 2 also instead of 1 (last line)
     
  3. DickCappels

    Moderator

    Aug 21, 2008
    5,533
    1,730
    It might help if you describe the help you are looking for, such as what modifications you want to make to the filters.
     
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