MEMS microphone fully-integrated CMOS cap-less preamplifiers

A pair of completely integrated capless preamplifiers (not requiring external capacitance) for MEMS microphones are presented. The devices exploit specific circuit solutions to implement a proper dc biasing of the pre-amplifier and a low frequency (< 1 Hz) high-pass pole. The two solutions adopted are a based on a transistor in the off state (OTP) and a switched-resistor (SRP), respectively. Since the devices are supposed to operate with different silicon microphones, the pre-amplifier gain has to be programmable. In spite of the single ended configuration and independently of the gain, both pre-amplifiers achieve a signal to noise ratio (SNR) lower than −100 dB. The total harmonic distortion (THD) is lower than −80 dB for the OTP and lower than −100 dB for the SRP. The devices are implemented in a 0.18-μm CMOS technology, with a supply voltage of 1.8-V. In both cases the power consumption is 230 μW. The bandwidth of interest ranges from 20 Hz to 20 kHz. Both solutions have variable gain configurations [−6, 0, 6, 12, 18] dB.

[1]  Sergio Pernici,et al.  A high-performance analog front-end 14-bit codec for 2.7-V digital cellular phones , 1998 .

[2]  Marian Verhelst,et al.  A 90 nm CMOS, $6\ {\upmu {\text{W}}}$ Power-Proportional Acoustic Sensing Frontend for Voice Activity Detection , 2016, IEEE Journal of Solid-State Circuits.

[3]  Hariprasad Chandrakumar,et al.  5.5 A 2µW 40mVpp linear-input-range chopper- stabilized bio-signal amplifier with boosted input impedance of 300MΩ and electrode-offset filtering , 2016, 2016 IEEE International Solid-State Circuits Conference (ISSCC).

[4]  Andrea Baschirotto,et al.  A 106 dB A-Weighted DR Low-Power Continuous-Time $\Sigma \Delta $ Modulator for MEMS Microphones , 2016, IEEE Journal of Solid-State Circuits.

[5]  A. Baschirotto,et al.  A 828μW 1.8V 80dB dynamic-range readout interface for a MEMS capacitive microphone , 2008, ESSCIRC 2008 - 34th European Solid-State Circuits Conference.

[6]  M. Grassi,et al.  A 0.13μm-CMOS 90μW 51dB-SNR continuous-time accelerometer front-end with 10b SAR-ADC , 2015, 2015 IEEE SENSORS.

[7]  Marian Verhelst,et al.  A 90 nm CMOS, 6µW Power-Proportional Acoustic Sensing Frontend for Voice Activity Detection , 2016, IEEE J. Solid State Circuits.

[8]  G. Nicollini,et al.  A 1.8 V 14 b audio front end codec for digital cellular phones , 1999, 1999 IEEE International Solid-State Circuits Conference. Digest of Technical Papers. ISSCC. First Edition (Cat. No.99CH36278).

[9]  Germano Nicollini,et al.  100${+}$ dB A-Weighted SNR Microphone Preamplifier With On-Chip Decoupling Capacitors , 2012, IEEE Journal of Solid-State Circuits.

[10]  Rahul Sarpeshkar,et al.  A low-power high-PSRR current-mode microphone preamplifier , 2003, IEEE J. Solid State Circuits.

[11]  Hao Gao,et al.  A 0.20 mm2 3 nW Signal Acquisition IC for Miniature Sensor Nodes in 65 nm CMOS , 2016, IEEE J. Solid State Circuits.