Improved unity-STF sturdy MASH ΣΔ modulator for low-power wideband applications
A novel sturdy multi-stage noise-shaping sigma–delta modulator that cancels the first-stage quantisation error at the output of the modulator is presented. Since any stage of the modulator has unity signal transfer function, the modulator would be very robust to circuit non-idealities such as finite op-amp gain. Furthermore, the signal processing timing issue in the critical paths of the proposed topology has been relaxed due to shifting the delay of the last integrator to the feedback path of the modulator. Moreover, this topology can be implemented in the circuit level by a fewer active blocks. Therefore, it practically would be suitable for low-voltage and low-oversampling applications. Simulation results show the usefulness of the proposed modulator.
