An improved sigma-delta modulator for digitizing carrier band measurements

Abstract

Draper Laboratory currently employs a third-order Sigma-Delta modulator to digitize the outputs from microelectromechanical sensors at the intermediate frequency prior to demodulation inside a field programmable gate array. This modulator, which is built on a .5[mu]m CMOS process, is to be used as a standalone chip or as a core for use in larger microelectromechanical sensor integrated circuits. In this document, I submit the design of an improved Sigma-Delta modulator, which has a noise floor of 40nV/ [square root of] Hz and a 5Vpp input range.