This paper presents mathematical formulae showing that the distance mismatch for an uncentered proof mass in an accelerator sensor does not influence the linearity of the closed-loop accelerometer as a whole. This asymmetry in sensors only introduces an output voltage offset in the readout integrated circuit. Numerical simulation using Matlab/Simulink confirms the mathematical conclusion. The linear response after compensation with a conventional capacitor array is also simulated and analyzed. Results show that there is a loss in linearity. Similar results hold not only for the continuous-time architecture, but also for a time-divided architecture. A readout integrated circuit with a time-divided architecture is designed and fabricated using a 0.35 µm HV CMOS process. An accelerometer composed of a microelectromechanical system sensor with severe built-in distance mismatch and the designed readout integrated circuit is tested. Test results show that the nonlinearity of such accelerometer is within 0.3%.
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