Analysis of sigma-delta converters for MEMS sensors using power supply voltage as reference

The paper considers the readout and analogue-to-digital conversion circuitry of the output signals coming from sensors, especially MEMS sensors. The study focuses on the effects that take place when the supply voltage is used as reference voltage for the system instead of the usual reference voltage produced by a band-gap circuit (sigma-delta modulator ratiometric with respect to the power supply). This replacement allows us to save the power dissipated by the band-gap circuit and by the reference buffers, thus optimising the power consumption of the system. The presented results show which are the effects on the converter resolution when its reference voltage is not stabilised