• Resolved

About microphone IC product

Hello,

We are working on the microphone input chain on the MSP430f5438 expermenter board, whose schematic is showed below.

We simulated it in Multisim and it showed a cutoff frequency of around 4kHz for the low-pass filter. But for our application, we need that to be more than 10kHz. Since we have many same boards need this modification, I would like to ask if there is any commercial IC product available for this. Maybe something similar to the following circuit (I saw it from another one's post in this forum).

Regards

  • Ximeng,

    The op amp you are using does not have a sufficient gain-bandwidth product to provide a gain of 240 with a bandwidth of 10kHz. The gain * bandwidth of the TLV2760 is only 500kHz. The gain * bandwidth of your circuit is approximately 2.5MHz. An op amp with a gain-bandwidth of 5MHz or so would probably give you reasonable results.

    An alternative is to break the gain into two stages of approximately 15 each. In this case, the TLV2760 would be sufficient.

    Regards, Bruce.

  • In reply to Bruce Trump:

    Hello Bruce,

    Thank you for replying. Could you give me a hint about which op-amp we should propably use for our application?

    And is there something commercial available which contains the circuit with suitable op-amp? Since we have a lot of boards need modification.

    Regards and Thank you,

    Ximeng

  • In reply to ximeng mao:

    Ximeng,

    I recommend the OPA314 with 3MHz gain-bandwidth. I am not aware of any special purpose device for this function. I recommend using an op amp.

    Regards, Bruce.

  • In reply to Bruce Trump:

    Thank you very much!!