Comparative Study for Different Loop-Filter Architectures of 2x Time-Interleaved CT DSM

In this paper, we make a comparative study between existing architectures of two channel (2x) time-interleaved (TI) continuous-time (CT) delta-sigma modulator (DSM), namely, cascaded integrators feedforward (CIFF)-based architecture and cascaded integrators feedback (CIFB)-based architecture. The comparison is made in terms of the required DAC numbers, the input branches of the adders as well as the output swing of each integrator. Then, we propose a CIFF-FB-based 2x TI CT DSM through detailed derivations while the proportional integrator (PI) technique is used to simplify the overall architecture (e.g. the required DAC numbers). The proposed architecture has been simulated using behavioral models. It is shown that the CIFF-FB-based loop filter using the PI technique can be considered as a promising candidate implementing a 2x TI CT DSM, in terms of hardware consumptions and dynamic performance.