Knowles’ SPG08P4HM4H-1, a.k.a ‘Baracus’, is a multimode digital top port microphone from their SiSonic™ range of surface-mount MEMS microphones. The Baracus is a miniature, top port silicon microphone with a single-bit PDM output. The component consists of an acoustic sensor, a low-noise input buffer, and a sigma-delta modulator, and it was designed for use in a myriad of portable electronic devices where excellent wideband audio performance and RF immunity are required. With a low-frequency rolloff at 30 Hz and high-frequency flatness at 10 kHz (resonance peak at 20 kHz), the device should be capable of capturing a useful range of audible sound while rejecting rumble. Moreover, 64 dB Signal-to-Noise Ratio (SNR) and ±1 dB sensitivity matching greatly improves audio algorithm performance, including beam forming and noise suppression, and noise-immune duplex PDM output enables multi-mic architectures and eases system integration.
In addition to these audio specs, the Baracus offers multiple performance modes for minimising power consumption. With a Vdd of 1.65 V to 3.6 V, the typical supply current in normal mode is a mere 170 µA to 1250 µA (depending on the clock frequency), with 290 µA in low-power mode and 35 µA in sleep mode. The Baracus comes in a 4.0 x 2.0 x 1.1 mm package with 6 pads: data, ground, Vdd, clock, ground, and select.
Knowles produces a universal evaluation kit for simple-and-easy testing of their SiSonic MEMS microphones, which are available on flexible bias boards for interfacing with the main board, the KAS-33100-0004, a.k.a. ‘Muskie’. With it, engineers can evaluate two input channels of audio from multiple MEMS microphone types, whether these be single or differential analog MEMS microphones, digital PDM MEMS microphones like Baracus, or Digital I2S MEMS microphones. Clock frequencies are easily selectable during testing, as are voltages and gains, and multiple audio outputs – XLR, 3.5mm Headset Jack, USB Audio – allow for extremely flexible monitoring and data capture.
(All images sourced from Knowles)