Design, fabrication, and testing of a 12-bit sigma-delta analog to digital converter

A 12-b sigma-delta ( Sigma - Delta ) analog-to-digital (A/D) converter has been designed and fabricated using a 2- mu m CMOS double-poly process. The chip is part of a study in the design of mixed analog-digital circuits. A second-order Sigma - Delta modulator using 1 b quantization and a subsequent moving average digital filter using no multiplies have been realized. Simulations were run to determine layout accuracy. The A/D converter occupies roughly 3/4 of a 2.22-mm*2.25-mm MOSIS tiny chip. The chip has been fabricated through MOSIS. Preliminary test results are reported.<
>