9.5 A 1.8V true-differential 140dB SPL full-scale standard CMOS MEMS digital microphone exhibiting 67dB SNR

Bach, Elmar; Gaggl, Richard; Sant, Luca; Buffa, Cesare; Stojanovic, Snezana; Straeussnigg, Dietmar; Wiesbauer, A.

doi:10.1109/isscc.2017.7870313

Cited by 21 publications

(21 citation statements)

References 3 publications

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“…It is composed of two single-ended channels which, combined in a pseudo-differential architecture, present full integration with dual-backplate (DBP) MEMS microphones. This kind of transducer is built by adding a second backplate to the conventional single-backplate (SBP) MEMS microphone, resulting in a differential capacitive sensor with even-order harmonics cancellation [8]. In the presented architecture, both the positive (P) and the negative (N) channels are identical.…”

Section: System Level Architecturementioning

confidence: 99%

“…Figure 8 shows the simplified schematic of the analog core for the single-ended channel configuration in the proposed VCO-ADC. The MEMS sensor is biased by a high-ohmic biasing circuit [8] and a NMOS (M0) transistor in the common-drain amplifier configuration. M0 acts as a voltage buffer stage that adapts the high-impedance input signal x(t) into the low-impedance output signal v(t).…”

Section: Circuit Designmentioning

confidence: 99%

“…In recent years, to meet these basic needs, conventional Electret Condenser Microphones (ECM) have been replaced by Microelectromechanical systems (MEMS) sensors [4,5,6,7]. The MEMS high signal-to-noise ratio (SNR), good sensitivity, and the possibility to place a large number of these sensors in the same device make this technology well suited for current audio applications [8,9].…”

Section: Introductionmentioning

confidence: 99%

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A VCO-Based CMOS Readout Circuit for Capacitive MEMS Microphones

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et al. 2019

Sensors

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Microelectromechanical systems (MEMS) microphone sensors have significantly improved in the past years, while the readout electronic is mainly implemented using switched-capacitor technology. The development of new battery powered “always-on” applications increasingly requires a low power consumption. In this paper, we show a new readout circuit approach which is based on a mostly digital Sigma Delta (sans-serifΣΔ) analog-to-digital converter (ADC). The operating principle of the readout circuit consists of coupling the MEMS sensor to an impedance converter that modulates the frequency of a stacked-ring oscillator—a new voltage-controlled oscillator (VCO) circuit featuring a good trade-off between phase noise and power consumption. The frequency coded signal is then sampled and converted into a noise-shaped digital sequence by a time-to-digital converter (TDC). A time-efficient design methodology has been used to optimize the sensitivity of the oscillator combined with the phase noise induced by 1/f and thermal noise. The circuit has been prototyped in a 130 nm CMOS process and directly bonded to a standard MEMS microphone. The proposed VCO-based analog-to-digital converter (VCO-ADC) has been characterized electrically and acoustically. The peak signal-to-noise and distortion ratio (SNDR) obtained from measurements is 77.9 dB-A and the dynamic range (DR) is 100 dB-A. The current consumption is 750 μA at 1.8 V and the effective area is 0.12 mm2. This new readout circuit may represent an enabling advance for low-cost digital MEMS microphones.

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Section: System Level Architecturementioning

confidence: 99%

Section: Circuit Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A VCO-Based CMOS Readout Circuit for Capacitive MEMS Microphones

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“…In fact, technologies, like the cancelation of ambience noise, need additional than one microphone per unit, increasing the demand for low-power low-cost electronic circuit even more. Multimedia microphones has some benefits over analog mics (e.g., improved rejection of power supply), and the pattern shows that they could gain attention in the approaching future [20]. A traditional electronic microphone comprises of an analogue microphone attached to an analog to digital (ADC) portable low-power converter.…”

Section: Introductionmentioning

confidence: 99%

Design of a Linear Voltage to Frequency Converter for Digital Audio Applications

Prince*,

Immanuel,

et al. 2019

IJITEE

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Voltage to frequency converters are used in various types of analog to digital converters in suitable digital audio applications. One of the applications is the Audio Interface which has been considered. The Voltage to frequency converter (VFC) thus plays a major role in the analog to digital conversion. This paper proposes a low power VFC designed in 0.18 µm technology which in turn is used to design a low cost and a high-resolution analog to digital converter (ADC). The analog signal is given to the V-F converter and the VFC output is given to the frequency counter using a suitable link. This counter gives the digital output. The design is implemented in PSoC and the performance is analysed with the previous technologies. Parameters such as sensitivity, output frequency and power consumption are analysed. This V-F converter and ADC are used in the digital audio interface which is used for audio applications. With the proposed VFC and ADC, the interface produced a good SNR compared to the conventional audio interfaces.

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“…In the year 2017, Infineon Technologies presented a paper in the literature about a digital CMOS MEMS microphone with an improved SNR of 67 dB [153]. This is a dual-back plate microphone with a supply voltage of 1.8 V achieving a sensitivity of -46 dBFS and a sound pressure level (SPL) of 140 dB.…”

mentioning

confidence: 99%

Design Approaches of MEMS Microphones for Enhanced Performance

Shah

Lee

et al. 2019

Journal of Sensors

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This paper reports a review about microelectromechanical system (MEMS) microphones. The focus of this review is to identify the issues in MEMS microphone designs and thoroughly discuss the state-of-the-art solutions that have been presented by the researchers to improve performance. Considerable research work has been carried out in capacitive MEMS microphones, and this field has attracted the research community because these designs have high sensitivity, flat frequency response, and low noise level. A detailed overview of the omnidirectional microphones used in the applications of an audio frequency range has been presented. Since the microphone membrane is made of a thin film, it has residual stress that degrades the microphone performance. An in-depth detailed review of research articles containing solutions to relieve these stresses has been presented. The comparative analysis of fabrication processes of single- and dual-chip omnidirectional microphones, in which the membranes are made up of single-crystal silicon, polysilicon, and silicon nitride, has been done, and articles containing the improved performance in these two fabrication processes have been explained. This review will serve as a starting guide for new researchers in the field of capacitive MEMS microphones.

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9.5 A 1.8V true-differential 140dB SPL full-scale standard CMOS MEMS digital microphone exhibiting 67dB SNR

Cited by 21 publications

References 3 publications

A VCO-Based CMOS Readout Circuit for Capacitive MEMS Microphones

A VCO-Based CMOS Readout Circuit for Capacitive MEMS Microphones

Design of a Linear Voltage to Frequency Converter for Digital Audio Applications

Design Approaches of MEMS Microphones for Enhanced Performance

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