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OPA4180: filter

Yuta Nishie
Genius 3030 points
Part Number: OPA4180

Hi,

The chopping frequency is 650 kHz, but is it OK to use as 3rd order LPF of 3 kHz?
And do I need to add a filter that suppresses 650 kHz?

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/565589/opa180-opa180-chopping-frequency?tisearch=e2e-sitesearch&keymatch=OPA180%20chopping#

Best Regards,

Nishie

  • +1
    TI__Guru* 93105 points

    Neshie-san,

    The OPA4180 uses an internal chopping frequency of 650 kHz as you have noted, but noise current spikes created by the chopping are filtered by the internal sin(x)/x notch filter. Additionally, the 3 kHz active low-pass filter circuit which the OPA4180 is a part of will further filter and attenuate the 650 kHz noise. It should not be necessary to add a separate 650 kHz filter.

    Regards, Thomas

    Precision Amplifiers Applications Engineering