PDM Microphone Aggregation

Data aggregation and bridging between devices supporting various protocols in audio space

Pulse Density Modulation (PDM) is a popular way to deliver audio from microphones to the signal or application processors inside mobile and IoT devices. PDM is ideally suited for this task because it brings the benefits of digital, such as low noise and freedom from interfering signals, at low cost.

For signal processors that do not have enough PDM inputs or have one or no I2S interfaces, the iCE40 UltraPlus microphone aggregation reference design allows the connection of up to eight microphones to a processor over I2S or SPI bus.

Multiple microphones are becoming widely used in personal assistance devices for audio beamforming. A microphone array is used to form a spatial filter, which can extract a signal from a specific direction and reduce the contamination of signals from other directions.

  • Aggregate up to 8 PDM microphones and connection to a processor over I2S or SPI
  • Excellent system function response that does not affect audio quality
  • Supports 3.072 MHz PDM clock and 12.288 MHz I2S clock
  • PCM output at 48 KHz
  • Support beamforming capability by using multiple microphones

Block Diagram

Documentation

Quick Reference
Technical Resources
Downloads
TITLE NUMBER VERSION DATE FORMAT SIZE
iCE40 UltraPlus 6 to 1 MIC Aggregation SPI Demo Radiant User Guide
FPGA-UG-02057 1.0 6/26/2018 PDF 907.1 KB
TITLE NUMBER VERSION DATE FORMAT SIZE
iCE40 UltraPlus 8 to 1 Microphone Aggregation Bitstream
1.0 1/2/2018 ZIP 47.7 KB
iCE40 UltraPlus 8:1 Mic Aggregation Demo User Guide
FPGA-UG-02035 1.2 2/26/2018 PDF 1.6 MB
TITLE NUMBER VERSION DATE FORMAT SIZE
iCE40 UltraPlus 8 to1 Microphone Aggregation Radiant Source Files
1.0 6/14/2018 ZIP 5.2 MB
iCE40 UltraPlus 6 to 1 MIC Aggregation SPI Demo Radiant Source Files
1.0 6/29/2018 ZIP 48.7 MB