Low distortion and swing suppression sigma-delta modulator with extended dynamic range scheme

Abstract

This work presents a new low distortion and swing suppression second order sigma-delta modulator with extended dynamic range scheme. The proposed modulator is based on the dual-quantizer architecture and can effectively extend the dynamic range by only adding two simple digital filters in the digital circuit. The techniques of low distortion and swing suppression integrator designs are also employed in the new architecture. Accordingly, this new architecture can improve the circuitry nonlinearity, and the in-band noise can be significantly suppressed to achieve a high resolution in mid or wide bandwidth applications. A second order SDM for Bluetooth application with bandwidth of 500 KHz and sampling frequency of 40 MHz was designed and implemented. The peak SNDR of the experimental SDM is 78 dB.