Suppression of Switch Mode Power Supply Noise in Digital Microphones
A digital microphone has a high power consumption compared to an analog. This will result in a higher working temperature, especially if traditional linear regulators are used in the microphone power supply circuitry. For a better degree of power efficiency, a switch mode power supply can be used instead. A switch mode power supply will however add noise. If the pulse width modulator is synchronised to the analog-to-digital converter sample rate clock, the switch mode power supply noise decreases by elimination of the alias frequencies.
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