A 2-path bandpass sigma-delta modulator utilizing blue-noise path selection

We present a pseudo-two-path bandpass sigma-delta (SigmaDelta) modulator design that improves upon current designs by completely suppressing the mirror image in the input signal band. The proposed SigmaDelta modulator structure introduces a resonator consisting of four total paths that are selected in a blue-noise manner, which serves to spread the mirror image caused from path mismatch across the entire signal bandwidth. A specific example of a two-path modulator utilizing a modulator based on a pseudo-two-path structure with blue-noise randomized capacitor path selection is described. The proposed design improves SFDR performance over traditional pseudo-two-path designs. Additionally, it is shown that the proposed structure demonstrates SNR improvement over a wide range of practical oversampling ratios. Behavioral simulations of this design show improvements to the SFDR of up to 21 dB and SNR up to 7.9 dB from previous two-path techniques