The new VM3011 MEMS microphone further extends Vesper’s technology leadership in the low-power always-listening device market, and expands applications for the company's patented piezoelectric MEMS transducer technology. The Adaptive ZeroPower Listening (ZPL) technology automatically "learns" the acoustic characteristics of the environment in real-time, allowing the system to ignore background noise and only wake in response to keywords or other desired acoustic triggers. By automatically adjusting the background threshold based on the acoustic level of the environment, this allows the system to hibernate over 90% of the time and extend battery life >10x.
When combined with the ultra-fast startup of piezo microphones, the VM3011 enables unprecedented system power savings for voice-activated devices without compromising the acoustic performance. The VM3011 uses a bottom port and integrates both the ASIC and the piezoelectric MEMS transducer in the same package.
A digital PDM interface is available to stream the audio data while an I2C interface allows “on the fly” configuration of the Adaptive ZPL. The VM3011 uses the PDM clock speed to change device modes. The DATA pin outputs PDM output in normal mode operation. In Wake on Sound (WoS) mode, a Digital Output pin (DOUT) outputs a single bit “Threshold Exceeded” flag when the acoustic input is greater than the set threshold. When the required threshold is reached, the microphone sends an interrupt signal to the external codec or voice processor using the DOUT pin.
The microphone is constantly listening to the environment with just 10 μA of current consumption. Adaptive Mode continuously measures the average sound level of the environment and adjusts the internal WoS threshold comparator until it converges to the threshold margin configured using the I2C register. This margin can be set to a range 6-18 dB above the average acoustic noise level.
"Existing always-listening systems run continuously and must be plugged into an electrical outlet. The VM3011 creates a new paradigm where these systems can now run for months or years on battery power,” says Matt Crowley, CEO of Vesper. “This technology will power a new class of products such as always-listening far field TVs, always-listening smartwatches, home security cameras and doorbells and many other systems. Vesper has already engaged with lead customers who plan to roll out products with the VM3011 later this year."
Like any Vesper piezoelectric MEMS device, the VM3011 has native IP57 rating for operation in environmentally robust applications, and does not require any external protective mesh. This translates to saving device manufacturers’ costs, but also increases the acoustic performance of the end application.
The VM3011 will be available in volume production by Q4 2020, in a small industry-standard 3.76 mm X 2.95 mm X 1.3 mm package, and it’s reflow solder compatible with no sensitivity degradation.