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Design a active filter with LMV794

syed hamad
Expert 1120 points
Other Parts Discussed in Thread: LMV794

Hi Guys,

Pls help me design a active filter with LMV794 with the center frequency of 160000Hz. If I am trying to design a filter with filterpro the required opamp GBW is 1.6GHz and 2.2GHz. So please support me to get the good filter design with LMV794 whose GBW is 88MHz..

waiting for your valuable feedback.

regards,

syed

  • TI__Guru* 93105 points

    Syed,

    You shouldn't use an operational amplifier that has too low of GBW relative to what FilterPro recommends. You will find that the filter response becomes more and more distorted as the GBW deviates from that which is recommended. The center frequency will move lower, the gain will not be correct and the filter skirts will deviate from the correct roll-off. Phase and delay characteristics will be distorted as well.

    If FilterPro is returning very high GBW, then you may have some very steep filter requirements that warrant the very wide bandwidth. High frequency, high gain, high "Q" and demanding responses such as a Chebyshev response all contribute to a filter requiring very high GBW operational amplifiers. Take some time to assess what you really need and you may find that you with less demanding filter requirements the GBW drops off. You may find that a Butterworth response and reasonable gain per stage results in much lower GBW requirements.

    Also, your band-pass filter has a center frequency of 160 kHz. That frequency is within the realm of practical LC filters should you not be able to e able to satisfy the requirement with an active filter.

    Regards, Thomas

    PA - Linear Applications Engineering