A double-sampling cross noise-coupled Sigma Delta modulator with a reduced amount of opamps

This paper presents the design of a second order double-sampling split path Sigma Delta modulator with cross noise-coupling. The power budget for the double-sampling is reduced by using bilinear integrators, while cross noise-coupling between the two modulator loops increases the noise shaping to third order. The implementation of the noise-coupling is incorporated into the second integrator using a novel delaying feed-forward circuit. The complete modulator is integrated in a 130nm CMOS technology and operates at a 120 MHz clock frequency. It achieves 77.8dB dynamic range and 71.4dB SNDR over a 5MHz bandwidth.