Page 18 - EE Times Europe Magazine | June2020

18 EE|Times EUROPE

The Growing Importance of Innovative MEMS Microphones

the membrane. These kinds of extreme membrane dis-
placements cause distortion. The second challenge is
to design an ASIC capable of handling the large signal
that the MEMS element generates. As audio-process-
ing algorithms assume a linear signal, any distortions
above 1% can cause a significant reduction of the audio
quality on which advanced audio processing relies.
One approach is to implement a MEMS sensor
element that places the moving membrane between
two capacitor plates (dual backplate, or DBP). A DBP
MEMS microphone minimizes distortion due to its
symmetrical construction. The same effect is achieved
by moving two membranes that sandwich the capaci-
tor plate (dual membrane).

SEALED DUAL-MEMBRANE TECHNOLOGY Figure 5: MEMS microphones with robust sealed dual-membrane technology
The introduction of DBP technology has produced a (SDM) set the SNR and AOP benchmarks.
significant increase in linearity specifications com-
pared with MEMS microphones with a single backplate.
The next evolutionary step is capacitive MEMS microphones with an quality to water and dust robustness to size and cost. Infineon offers a
SDM. Sealing the capacitance area enables practically noise-free audio portfolio of XENSIV™ MEMS microphones that ranges from low-cost
signal capture. This increases the SNR further, from 70 dB up to 75 dB models to products that deliver the highest performance levels. Devices
(Figure 5). The first prototypes have already achieved an SNR of 75 dB with a single backplate are robust and cost-effective but have lim-
and an AOP of 135 dB SPL. The first devices in this new generation have ited acoustic performance, whereas MEMS devices with DBP provide
already been used to demonstrate the advanced audio features discussed improved acoustics. SDM technology combines the highest acoustic
above. By the end of 2020, Infineon will introduce further shrunk-sealed performance (SNR up to 75 dB) with high robustness (IP 57). SDM
dual-membrane microphones targeted at space-constrained devices. MEMS microphones with best-in-class SNR are robust against dust
and water and are the ideal choice for emerging applications such as
CONCLUSION high-quality video/audio conferencing and medical tracking. ■
Microphone technology is becoming increasingly important as the
number of audio applications and features rise. Different factors have REFERENCE
to be considered for a variety of applications, ranging from audio 1 Digital and Voice Interface Forecast, October 2018

NEWS

Imagination Inquiry Exposes IC Unit Shipments

Wider Risk of IP Sales to China Face First-Ever
Back-to-Back Decline
Imagination Technologies’ now-defunct defended their business strategies. Imagi-
plan to add four Chinese investors to its nation’s revenue has steadily declined since
executive board has touched a raw nerve 2017, and its recovery path has pitted former Market researcher IC Insights forecasts that
in the U.K. and triggered a series of events CEOs Hossein Yassaie and Ron Black, as well worldwide IC unit shipments will register
leading to a full-blown government inquiry. as former senior executive John Rayfield, their first-ever back-to-back annual decline
In a three-hour hearing before the U.K. against interim CEO Ray Bingham, who in 2020. Prior to 2019, the previous four years
Parliament’s Foreign Affairs Committee, favored the involvement of Chinese backers. that IC unit shipments declined were 1985,
three Imagination CEOs, past and present, None of the issues were resolved. The 2001, 2009, and 2012. From 2013 through
were grilled in a public battle to preserve committee tried to unravel the drama that 2018, IC unit shipments were on a respect-
the IP developer’s legacy. The public debate sparked the questions — the departure of able growth path, with an 8% increase logged
centered on the suitability of Imagination Black and Rayfield as well as former senior in 2013, a 9% jump registered in 2014, a 5%
owner Canyon Bridge Partners’ recent executive Steve Evans — and fears that increase displayed in 2015, a 7% increase
attempt to add new Chinese directors to Imagination would relocate to China. shown in 2016, a double-digit growth rate of
the board and the government’s role — if The bigger picture — IP licensing and 15% in 2017, and a 10% increase in 2018.
any — in protecting home-grown intellec- security risks represented by China — isn’t In contrast to the double-digit increases
tual property (IP). unique to the U.K. Electronics companies in 2017 and 2018, 2019 marked only the fifth
Tech industry executives watched the live view the lucrative Chinese electronics market time in the history of the IC industry that IC
online event as factions within Imagina- as fiscal salvation; governments greet China’s unit shipments registered a decline, according
tion’s past and present senior leadership foreign-investment plans with suspicion. to IC Insights.

JUNE 2020 | www.eetimes.eu