This paper proposes two fully-integrated cap-less (i. e. without external capacitor) preamplifiers for silicon microphones. Proper dc biasing of the preamplifier is obtained with two solutions to implement a large feedback resistance (in the GO range), based on a switched resistor and a transistor in the off state, respectively. Both solutions have been implemented in a 0.18-μm CMOS technology and consume 230 μW from a single 1.8-V power supply. Both preamplifiers achieve a flat frequency response between 20 Hz and 20 kHz with a programmable gain ranging from -6 dB to +18 dB, and an integrated input referred noise (IIRN) lower than -100 dBV. The achieved total harmonic distortion (THD) is lower than -100 dB and -80 dB for the switched-resistor and the off-transistor preamplifiers, respectively, independently of the gain and in spite of the single ended configuration.
Croce, M., De Berti, C., Crespi, L., Malcovati, P., Baschirotto, A. (2017). Cap-less audio preamplifiers for silicon microphones. In Proceedings of IEEE Sensors (pp.1-3). Institute of Electrical and Electronics Engineers Inc. [10.1109/ICSENS.2016.7808720].
Cap-less audio preamplifiers for silicon microphones
BASCHIROTTO, ANDREAUltimo
2017
Abstract
This paper proposes two fully-integrated cap-less (i. e. without external capacitor) preamplifiers for silicon microphones. Proper dc biasing of the preamplifier is obtained with two solutions to implement a large feedback resistance (in the GO range), based on a switched resistor and a transistor in the off state, respectively. Both solutions have been implemented in a 0.18-μm CMOS technology and consume 230 μW from a single 1.8-V power supply. Both preamplifiers achieve a flat frequency response between 20 Hz and 20 kHz with a programmable gain ranging from -6 dB to +18 dB, and an integrated input referred noise (IIRN) lower than -100 dBV. The achieved total harmonic distortion (THD) is lower than -100 dB and -80 dB for the switched-resistor and the off-transistor preamplifiers, respectively, independently of the gain and in spite of the single ended configuration.
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