Is a MEMS Microphone Analog or Digital?

MEMS (Micro-Electro-Mechanical Systems) microphones have revolutionized audio capture in consumer, automotive, and industrial applications. A common question is: are MEMS microphones analog or digital? The answer depends on the on-chip signal processing architecture—but most modern MEMS microphones on the market deliver a digital output, simplifying system integration and improving noise immunity.

Analog vs. Digital MEMS Microphones

1. Analog MEMS Microphones
   • Output: Low-level analog voltage proportional to sound pressure.
   • Requirements: External analog-front-end components such as anti-aliasing filters and ADCs (Analog-to-Digital Converters).
   • Use Cases: Legacy audio systems or designs where custom analog processing is needed.
2. Digital MEMS Microphones
   • Output: Integrated ADC provides a PDM (Pulse Density Modulation) or I²S digital data stream.
   • Advantages:
     • EMI Immunity: Digitization at the die prevents analog noise pickup on PCB traces.
     • Simplified BOM: Eliminates the need for external ADCs and filters.
     • Consistent Calibration: Factory-trimmed performance ensures tight part-to-part variation.
   • Use Cases: Smartphones, wearables, smart speakers, automotive voice control, and IoT sensors.

Key Interface Standards

• PDM (Pulse Density Modulation): One-bit data stream at a high clock rate; requires software decimation.
• I²S (Integrated Inter-IC Sound): Multi-bit serial audio with dedicated clock lines; lower firmware overhead.

Popular Digital MEMS Microphone Examples

• TDK InvenSense MEMS Microphone
  Industry-leading devices known for high SNR and low power consumption.
• Knowles Microphone
  Offers both analog and digital MEMS options optimized for medical and mobile markets.
• Infineon Microphone
  Combines robust automotive-grade qualifications with digital interfaces.

Notable Part Numbers

• IMP34DT05 / MP34DT05TR
  High-performance omnidirectional digital MEMS microphones featuring PDM output.
• V2S200D
  Though not a microphone, this MEMS gyroscope illustrates the broad MEMS sensor ecosystem.

Choosing the Right MEMS Microphone

When selecting between analog and digital MEMS microphones, consider:

• System Design Complexity: Digital mics reduce PCB routing and component count.
• Noise Environment: Digital outputs excel in high-EMI settings (automotive, industrial).
• Processing Resources: PDM requires onboard decimation filters; I²S passes PCM-ready data.

Explore SISTC’s complete range of digital MEMS microphones on our product category page.

Further Reading

• MEMS Microphone (Wikipedia): Overview of MEMS microphone technology and histories.
• Analog Devices: PDM vs. I²S Interfaces: Technical comparison of digital audio interfaces.
• STMicroelectronics: Digital Microphones Solutions: Comprehensive guide to digital MEMS microphones.