High performance ΣΔ closed loop accelerometer

This paper presents the system analysis, design and simulation of high performance seismic grade accelerometer interface. To date, all reported sigma-delta force feedback read out interfaces fall short of performance demanded by seismic grade instruments. In addition to the challenge of ensuring 20 bit resolution over a frequency band of few Hz to few hundred Hz, it has to achieve non-linearity in the order of 0.01% of full scale ranging ±g. In this paper we have analyzed major bottlenecks of state-of-the-art high order ΣΔ readout structures and have introduced improvement in the readout structure to overcome those shortcomings. Careful simulations of the proposed interface reveal that seismic grade performance can be achieved without burning more power or using higher order structure.