Design and Implementation of a Band-Pass Sigma Delta Modulator with Distributed Resonators

Continuous time band-pass sigma delta converters require the realization of high frequency resonators, which have been usually implemented with gm-C or LC circuits. However, transmission lines have been for a long time a standard way to implement high Q resonators in RF circuits. Recently, some continuous-time sigma&-delta (SD) modulator architectures using transmission lines have beenproposed. Theoretical analyses have shown that this kind of architectures share some of the properties of both continuous-time (CT) and discrete-time (DT) modulators. On the other hand they have specific implementation problemswhich are not present in other modulator architectures. This paper makes a brief review of the particularities of these modulators and shows the experimental results of a bandpass modulator implemented in BiCMOS technology. Asan advantage compared to standard continuous time designs, this modulator can be operated as a subsampling ADC, displays a better immunity to clock jitter and istolerant to loop delay.

Design and Implementation of a Band-Pass Sigma Delta Modulator with Distributed Resonators Articles