In this paper, a charge-balancing accelerometer is presented. A hybrid interface topology is utilised to achieve high resolution, high linearity and low power supply sensitivity. The accelerometer consists of a micromechanical sensor element, a self-balancing bridge (SBB) open-loop readout, AC force feedback and $Delta Sigma$ ADC. The SBB converts acceleration to ratiometric voltage. The ratiometric output of the SBB is converted to the digital domain by the ADC. In order to achieve high resolution, a micromechanical sensor element with a high quality factor, Q, is utilised. The AC force feedback is used for damping the high Q to get a low settling time. The sensor interface is fabricated in a standard 0.35 $mu$ m CMOS process. The fabricated chip has an area of 6.66 mm$^2$ and consumes 1 mA at a nominal supply voltage of 3.6 V. The sensor has a maximum DC nonlinearity of 1.3% over the commercial temperature range with an input range of ${pm} $1.15 g. The noise floor of the sensor is around 2 $mu{rm g}/sqrt{{rm Hz}}$ and the signal bandwidth is 200 Hz. The bias instability is 13 $mu$ g and the sensor gain variation is less than 5% in the 3–3.6 V supply range.
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