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Original question:

Multiple feedback band pass filter

LM359: Please help me find the right op amp

?? ?
Prodigy 30 points
Other Parts Discussed in Thread: LM359, OPA2891, TINA-TI

Tool/software:

I need an op amp that can amplify a 400kHz frequency signal by 150 times (forming a biased inverting AC amplifier and a multi-feedback bandpass filter).Can you recommend me some suitable op amps?Thank you so much

  • +1
    TI__Genius 15116 points

    Hello,

    Welcome to the E2E forum.

    Thanks for your question. I will push this thread to the proper group for comment regarding possible design options.

    In the mean time, can you answer the following questions:

    1. What supply voltage do you intend to use for the amplifier.

    2. What are your bandpass filter specifications (filter order, FL, FH)

    3. Does this amplified signal go to an ADC? What are the ADC specs if so.

    4. Do you have any noise requirements in this application? 

    I am going to start by sending this thread to our HSAMPS team who specialize in amplifiers above 50MHz GBWP. 

    Thanks,

    Jacob

  • 0
    Prodigy 30 points

    Hello
    Mr. Jacob.
    First of all, I am glad to receive your reply. Next, I will answer your questions.
    (1) Power supply problem. I will use a single power supply voltage of 12V.
    (2) Filter specifications. I want to use an MBF bandpass filter. The center frequency is about 435kHz. FL: 420kHz FH: 450kHz.
    (3) It will not be transmitted to the ADC.
    (4) I did not consider the noise problem. Because it is a high-frequency and high-precision signal processing, I want to choose the one with the lowest possible noise. The op amp currently used is LM359. As long as the noise value is lower than LM359, it will be fine.
    The above is my answer. Thank you again for your help. (My English expression is not very good, I hope you can understand my answer)

    Primary school students who like analog circuits

  • +1 in reply to ?? ?
    TI__Genius 15116 points

    Hello,

    I am happy to help you create this new design. Slight smile

    I have designed a circuit using TI's Filter Design Tool

    Here is my output for your filter settings:

    I have then used TINA-TI to simulate your circuit using OPA2891. 

    Here is the frequency response:

    Green is Vout, Red is vo1:

    We have an FL of 420kHz, FH of 450kHz, BPF centered at 435kHz, and we have a pass gain of 43.77dB = 154V/V. This is a 4th order BPF, so we have -40dB roll-off after the cutoff frequencies. 

    OPA2891 will have improved performance compared to a device like LM359. Note, this device will not be pin-pin compatible with LM359

    Please let me know if you have any questions.

    Best,

    Jacob