A Fully Differential Charge-Balanced Accelerometer for Electronic Stability Control Vladimir P . Petkov, Member , IEEE, Ganesh K. Balachandran , Member , IEEE, and

Abstract

An accelerometer for electronic stability control utilizes a two-mass mechanical sensor element to implement a fully-differential signal path, ac hieving robustness against elec- tromagnetic interference (EMI) without the need for external shielding in the package. The EMI rejection is augmented further with a pseudo-random chopping scheme, which spreads the in- terference over a wide bandwidth , reducing its in-band portion to the level of the noise floor. The chopping function maintains zero-mean voltage waveforms acr oss the sensor electrodes, which is also bene ficial for the long-term offset stability of the device. A charge-balanced capac itance-to-voltage converter provides linear transduction for displacements of the proof-mass up to 70% of the gap and minimizes the residual electrostatic forces. A dual-axis design occupies 1.1 mm in 0.18- m CMOS and consumes 820 A from an internally regulated 1.9 -V supply. The system achieves 380 noise floor and 84-dB dynamic range. The offset variation in the automotive temperature range of 40 to 140 C has a range of 11 mg.