Abstract
In some electronic devices, using a shunt capacitor to mitigate radio-frequency (RF) interference on a digital microphone (DMIC) data line can increase the capacitive load on the microphone's output driver. This increased load can elevate the thermal acoustic noise floor, creating a design trade-off between RF immunity and audio quality. Described herein is a hardware solution that can implement a resistor-capacitor low-pass filter on the DMIC's digital data line, where a series resistor is placed between the DMIC driver and the shunt capacitor. The series resistor may limit peak current drawn from the driver to help reduce thermal noise and can also soften the signal's digital edges to suppress high-frequency harmonics, thereby potentially reducing electromagnetic emissions. This configuration may help mitigate thermal acoustic noise and improve desense performance, allowing for improvements in both RF immunity and acoustic signal quality.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Ding, Shengyin and Xue, Mingfeng, "RC Filter for Concurrent Mitigation of Thermal Noise and Desense in Digital Microphones", Technical Disclosure Commons, ()
https://www.tdcommons.org/dpubs_series/10354