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We are making a stethoscope using MEMs digital Mic

Other Parts Discussed in Thread: OPA1633, OPA323, TAC5112, PCMD3140, PCMD3180

We are making a stethoscope using MEMs digital Mic  with 20hz to 20Khz and wish to use TI Preamp and Op Amp and are thinking to use OPA323 as Preamp and OPA1633 as amplifier for the HR and lung sounds which are in the range of:

30–500 Hz: heart sounds, especially S3;
80–500 Hz: lung sounds and heart valve clicks, S2 splits;
100–1000 Hz: lung sounds;
20–2000 Hz: wideband mode.

Amplification needed is 100x 

Are thes above two amplifiers okay to use or any other amplifier would be better?

  • Hi Anushka,

    From the information you have provided, it sounds like it could work! Most of the gain would be coming from the OPA323 which should have the bandwidth to support up to 20kHz. 

    Do you have any other requirements such as:

    - noise level? 

    - max input signal? 

    Best Regards, 

    Robert Clifton 

  • Hi, sorry to miss the important information. The mic that we are using is two digital MEMs microphones  IMP34DT05.

    One is to capture the heart beats and other for noise cancellation.

    For these Mics, Analog amplifier may not be compatible. However we are thinking to use TAC5112 in the circuit. The amplification is inbuilt in this. Will it be okay to go ahead with this?

  • Hi Anushka,

    Let me connect you with the team that is responsible for the TAC5112 so they can better assist you with this design. 

    Best Regards,

    Robert Clifton

  • Hi Anushka,

    If  you're just looking for digital mic support, I'd go with the PCMD3140/PCMD3180. It would provide digital mic -> I2S conversion and provide amplification and filtering. The TAC5112 is a codec and would be overkill for your application unless you wanted to take advantage of the DAC inside the codec.

    Best regards,
    Jeff McPherson