This paper presents a low power read-out front-end for 3-axis MEMS capacitive accelerometer. The front-end includes the analog preamplifier (to sense the signal coming from the MEMS) and a Successive-Approximation 10b A/D Converter, for digitalization and off-chip digital-signal-processing. Power minimization is achieved by using a continuous-time sensing preamplifier (i.e. constant-charge capacitance-to-voltage conversion) and SAR-ADC with bridge capacitive reduction. Preamplifier programmable in-band gain allows to accommodate different MEMS sensitivities. A very high-impedance MOS transistor is used for MEMS biasing, thus providing very low frequency (<1 Hz) AC coupling. In a 0.13 μm CMOS technology, the full channel consumes 90 μW from a single 1.2 V supply voltage, and achieves an equivalent 67.9 dBFull-Scale@SNR in [1 Hz–4 kHz] bandwidth by exploiting oversampling ratio.
De Matteis, M., Pezzotta, A., Sabatini, M., Grassi, M., Croce, M., Malcovati, P., et al. (2017). A 90 μW continuous-time front-end with 10b SAR-ADC for capacitive MEMS accelerometers. ANALOG INTEGRATED CIRCUITS AND SIGNAL PROCESSING, 92(3), 453-465 [10.1007/s10470-017-1009-0].
A 90 μW continuous-time front-end with 10b SAR-ADC for capacitive MEMS accelerometers
De Matteis, M
;Baschirotto, A
2017
Abstract
This paper presents a low power read-out front-end for 3-axis MEMS capacitive accelerometer. The front-end includes the analog preamplifier (to sense the signal coming from the MEMS) and a Successive-Approximation 10b A/D Converter, for digitalization and off-chip digital-signal-processing. Power minimization is achieved by using a continuous-time sensing preamplifier (i.e. constant-charge capacitance-to-voltage conversion) and SAR-ADC with bridge capacitive reduction. Preamplifier programmable in-band gain allows to accommodate different MEMS sensitivities. A very high-impedance MOS transistor is used for MEMS biasing, thus providing very low frequency (<1 Hz) AC coupling. In a 0.13 μm CMOS technology, the full channel consumes 90 μW from a single 1.2 V supply voltage, and achieves an equivalent 67.9 dBFull-Scale@SNR in [1 Hz–4 kHz] bandwidth by exploiting oversampling ratio.
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