A 2.5-rad/s2 resolution digital output MEMS-based rotational accelerometer for HDD applications

A 2.5-rad/s(2) resolution micro-electro-mechanical system-based rotational accelerometer targeted for hard disk drive (HDD) application is presented. The device is composed by a 0.6-mum BICMOS electronic interface that implements together with the MEMS sensor one single bit electromechanical SigmaDelta conversion loop able to detect capacitive unbalancing as low as 50 aF (50 (.) 10(-18) F). The produced bitstream is then processed by a digital chain and made available through a standard three-wire digital interface. The device is intended for feedforward compensation of external disturbances acting on computer HDDs to steadily keep the read-write heads on track and to allow greater track densities.