How to reduce or avoid microphone noise due to interference?

Nowadays, microphones are microphones, which are used more and more widely. With the digitization of artificial intelligence and the development of voice control technology, this demand is increasing day by day. In specific applications, many customers report that microphones are recorded or transmitted. The noise that will be generated is annoying. So, in the application circuit, can the microphone really bring noise? Or is it caused by a problem in the matching of the applied microphone circuit? , Now let’s analyze it.

Whether current players, smart speakers, or video players, there are a lot of interference sources, such as WiFi, Bluetooth, FM, PWM, switching power supply, these are all interference sources, these interferences are transmitted and radiated through the line The two ways in which the noise is transmitted will definitely be transmitted to the microphone, and the microphone will amplify these noises and transmit them back to the circuit, eventually forming an audible noise, which brings a bad experience to the customer.

Therefore, the so-called microphone noise, in fact, is mostly caused by poor circuit design. For example, the microphone is not grounded nearby. For example, the lead wire of the microphone is an ordinary electronic wire instead of a twisted pair or shielded wire. For another example, if the lead wire of the microphone is too close to such as: WiFi, Bluetooth, FM antenna, high-frequency oscillator, the circuit of the transmitting end, and the switching power supply circuit, obvious noise will be introduced.

So the author has the following suggestions. :
1. The microphone circuit should be as far away as possible from high-frequency circuits, switching power supply circuits, oscillating circuits, and circuits with large radiation.
2. Use shielded wires as much as possible for the lead wires of the microphone. If you don't need shielded wires in consideration of the cost, you should also use twisted-pair wires. Parallel wires or even two separate wires at random are not allowed. This will introduce more interference and noise.
3. The power supply circuit of the microphone must be added with high-frequency filtering and low-frequency filtering. In this way, ensuring that the power supply to the microphone is clean and the noise can be controlled to a greater extent.
4. The input circuit of the microphone should not use single-ended input as much as possible, but should use differential balanced input, which will help eliminate common mode noise.

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