116dB SFDR delta-sigma modulator with a novel GM-boost OPAMP for audio application

An low-power and high-resolution delta-sigma modulator for audio application is presented in this paper. The modulator applies single-loop six-order mixed feedforward single-bit quantizer topology. The mixed feedforward architecture can avoid the adder in the loop so as to save the hardware and decrease the power dissipation. Fully differential switched-capacitor circuit is applied to implement the modulator. The OPAMP is the most important module of the modulator. A novel gm-boost folded-cascade OPAMP is presented to keep high DC gain to acquire low-leakage and high linearity. The modulator presented achieves a SFDR of 116dB in a signal band-with of 20ksps with an oversampling ratio of 64.