This research investigates the use of oversampling techniques for digitizing signals in a 10MHz bandwidth with at least 13 bits of resolution. Although sigma-delta modulators have largely been implemented as discrete-time (DT) circuits, a continuous-time (CT) design approach appears to offer several advantages for realizing high-accuracy A/D converters at signal bandwidths where technology considerations may impose significant constraints. For a given technology and power dissipation, CT modulators can operate at higher sampling rates than DT circuits because the operational amplifier bandwidth required is significantly lower. CT modulators also provide inherent anti-alias filtering since sampling occurs at the quantizer input rather than at the modulator input. Finally, for the design objectives set forth in this program, the thermal noise of a CT modulator is lower than for a comparable DT design
Integrated Circuits Lab
Center for Integrated Systems
Stanford University