This brief proposes a new approach based on a tiny neural network to convert Pulse Density Modulation (PDM) signals acquired from digital Micro-Electro-Mechanical System (MEMS) microphones into the standard Pulse Code Modulation (PCM) format for any further digital audio processing. The proposed approach allows for a compact and ultra-low-power hardware implementation of the conversion, suitable for ultra tinyML Key Word Spotting (KWS) applications, closely coupled with the sensor itself and tightly coupled with a neural network classifier. The converter achieves a signal-to-noise ratio value of 48 dB, which enables KWS accuracy of 89% over 12 classes. Implementation on a Xilinx Artix-7 FPGA results in 917 LUTs, 361 FFs, and 182 μ W Dynamic Power (DynP) consumption. By targeting the TSMC 0.13 μm CMOS technology, the synthesis reports an area occupation of 0.086 mm2 and a DynP of 128.7 μ W /MHz. These results enable the integration of the proposed design into the CMOS circuitry closely coupled with the MEMS microphone.

A New NN-Based Approach to In-Sensor PDM-to-PCM Conversion for Ultra TinyML KWS

Vitolo P.;Liguori R.;Di Benedetto L.;Rubino A.;Licciardo G. D.
2023-01-01

Abstract

This brief proposes a new approach based on a tiny neural network to convert Pulse Density Modulation (PDM) signals acquired from digital Micro-Electro-Mechanical System (MEMS) microphones into the standard Pulse Code Modulation (PCM) format for any further digital audio processing. The proposed approach allows for a compact and ultra-low-power hardware implementation of the conversion, suitable for ultra tinyML Key Word Spotting (KWS) applications, closely coupled with the sensor itself and tightly coupled with a neural network classifier. The converter achieves a signal-to-noise ratio value of 48 dB, which enables KWS accuracy of 89% over 12 classes. Implementation on a Xilinx Artix-7 FPGA results in 917 LUTs, 361 FFs, and 182 μ W Dynamic Power (DynP) consumption. By targeting the TSMC 0.13 μm CMOS technology, the synthesis reports an area occupation of 0.086 mm2 and a DynP of 128.7 μ W /MHz. These results enable the integration of the proposed design into the CMOS circuitry closely coupled with the MEMS microphone.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/4823311
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 0
  • ???jsp.display-item.citation.isi??? ND
social impact