MEMS Microphones Gain Acceptance in Smartphones

On November 28 Akustica announced a new family of high-definition MEMS microphones. There are four versions with two analog and two digital and a top and bottom port for each. The company touts the new microphone family's high signal-to-noise ratio of 63dB, super wideband frequency response, and tightly matched +/- 2dB sensitivity.

Akustica's HD MEMS (micro-electro-mechanical system) microphones are drop-in replacements for most of the commonly used MEMS microphones. The company is offering a wide audio range up to 7kHz when transmitting, but it can record with a wider range of 14kHz. A key point is that Akustica offers top-port versions. This is a new packaging technology from Akustica.

Other top-port microphones have lower performance than a bottom-port microphone. Akustica's top-port has the same performance as its bottom-port version. A bottom-port microphone requires a hole in the PCB or flex circuit for mounting to the case. A top-port mounts on the other side of a board and is directly against the case. According to Akustica, customers are willing to pay a premium for a top-port microphone if it can offer this level of performance.

Akustica was acquired by Bosch Sensortec a few years ago. The microphones are manufactured by Bosch, thus leveraging the company's high-volume capability, quality, and reliability offered in the rest of its MEMS portfolio. The AKU142, AKU342, AKU240, and AKU440 are currently sampling to lead customers and will be ramping to mass production in the first quarter of 2013.

Semico's spin is that there is growing demand for high-quality MEMS microphones from the wireless carriers, mobile chipset suppliers, and mobile device manufacturers due to the growing popularity of user-generated content, such as videos. The audio quality is valued by consumers. The HD MEMS microphones enable better noise cancellation for both transmission and recording.

The first devices to feature Akustica's MEMS microphones are smartphones. Most smartphones now feature two microphones. Some, such as Apple's iPhone, have three. Tablet PCs and notebooks (ultraportables) have one microphone but are trending to more.

Semico Research Corp. foresees MEMS microphones as a fast-growing market. In 2011, Semico estimates just over 1 billion units shipped in all applications. By 2016, Semico projects, this market will exceed 5 billion units.