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carlosburgos
Level 1
Level 1
First question asked Welcome!

Hi, I am using the MEMS IM73A135V01, I have two questions. I already have an amplifier stage built so, can I connect the microphone directly to the amplifier stage or should I use the output load configuration with an Opamp as shown in the Datasheet? And the second question comes directly after the previous one, if it is necessary to build the output load configuration, where to connect the capacitors Ca, Cd, Cb?

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Yaran_W
Moderator
Moderator
Moderator
250 replies posted 100 solutions authored 25 likes received

hi @carlosburgos ,

1. It will depend on the specific requirements of your application and the capabilities of your existing amplifier stage. Here are some considerations to help you make the decision:

  1. Sensitivity and Noise: If amplifier stage provides sufficient gain and low noise levels for the signals from the MEMS microphone, you may be able to connect the microphone directly to the amplifier stage.

  2. Impedance Matching: Consider the impedance matching between the microphone and the amplifier stage. Some amplifier stages may require a specific input impedance for optimal performance with the MEMS microphone.

  3. Signal Conditioning: The use of an Opamp in the output load configuration can provide additional signal conditioning, such as filtering or impedance matching, which may be beneficial for your application.

  4. Power Requirements: Check if the power requirements of the MEMS microphone are compatible with the power supply capabilities of your amplifier stage.

  5. Frequency Response: Evaluate whether the frequency response of your amplifier stage meets the requirements of the MEMS microphone.

2.  Ca is typically used for DC blocking. It should be connected in series with the output of the MEMS microphone to block any DC offset that may be present. Cd is often used for decoupling or stabilization. It should be connected between the output of the Opamp and ground to stabilize the Opamp and prevent oscillations. Cb is usually part of a low-pass filter configuration. Its specific placement and value will depend on the desired frequency response and filtering requirements of your application.

Please refer to link:

https://community.infineon.com/t5/Knowledge-Base-Articles/Electrical-implementation-of-analog-microp...

https://www.infineon.com/dgdl/Infineon-AN558_MEMS_Electrical_Implementation-AN-v01_00-EN.pdf?fileId=...

 

BR

Yaran

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