N-path multirate sigma-delta modulator for high-frequency applications

An N-path multirate architecture for implementing a sigma-delta modulator (SDM) is proposed in this paper. The replacement of the first integrator in the N-path structure can relax the speed requirements of the opamps in the first stage. The use of comb filters in that integrator can also alleviate various mismatch effects. Comparison with conventional and other multirate SDM architectures is also presented. Simulation results show that the proposed architecture has several advantages when compared with previous implementations, such as low sampling frequencies, average performance for arbitrary N and reduced mismatch sensitivity between N paths.