A noise coupled ΣΔ architecture using a Non Uniform Quantizer

Abstract

A low power Discrete Time Sigma Delta modulator (DT SDM) for sensor applications is described in this paper. A third order noise shaping is reached with a second order loop filter due to the use of a noise coupling technique at the input of the quantizer. Using a Non Uniform Quantizer (NUQ) the hardware complexity is reduced. This architecture is suitable for high dynamic range sensor applications with some compression. Conventional mismatch shaping techniques can still be used to enhance linearity if a segmented DAC is used. At low amplitudes the NUQ is linearized by the noise coupling loop. A simulation example is presented, achieving a dynamic range of 103dB and a peak SNDR of 93dB over 25KHz bandwidth, and using a 1.6MHz clock.