Microphone bias refers to a small DC voltage applied to a microphone's input line to provide power to the microphone's internal electronics. This is commonly used for electret condenser microphones, which are widely used in headsets, smartphones, laptops, and other audio devices.
Purpose of Microphone Bias
-
Powering Electret Microphones:
- Electret condenser microphones require a power supply for their built-in pre-amplifier. The microphone bias provides this power.
- Without bias voltage, the microphone cannot convert sound into an audio signal effectively.
-
Simplified Power Delivery:
- The bias voltage is typically provided on the same line (signal line) as the audio signal. This simplifies the design by combining power and signal into one wire, reducing the number of connections needed.
-
Signal Conditioning:
- Bias voltage ensures the microphone has sufficient power to produce a usable signal level (amplitude).
- The microphone circuit uses this voltage to boost and stabilize the output signal.
How It Works
-
Voltage Source:
- A small DC voltage (usually 1.5V to 5V) is applied through a resistor to the microphone input line (mic bias).
- This voltage powers the FET (Field Effect Transistor) or pre-amplifier inside the microphone.
-
Signal Transmission:
- The microphone signal (AC audio) is superimposed on the bias voltage (DC). A capacitor later blocks the DC component, allowing only the audio signal to pass through to the amplifier or recording circuit.
Where Microphone Bias Is Used
- Headsets: Bias voltage powers the small electret mic in wired and wireless headsets.
- Smartphones and Laptops: Provided through the 3.5mm TRRS or USB connections for built-in and external microphones.
- Audio Interfaces and Radios: In devices using plug-in power for external microphones.
Summary
Microphone bias is a DC voltage used to power small microphones, particularly electret condenser microphones. It is essential for enabling the microphone to generate and amplify an audio signal. The bias is provided through the microphone signal line, simplifying power delivery in audio devices.
标签：what,power,signal,microphone,bias,voltage,audio From： https://www.cnblogs.com/archerqvq/p/18611537