Double sampling delta-sigma modulators

The double sampling technique can be used to achieve twice the sampling frequency in a sampled-data system without extra requirements for op-amp´s settling time, dc gain, etc. In this paper, theoretical analysis of path gain mismatch on the performance of double sampling delta-sigma modulators (ΔΣM´s) is given. Based on the result, a novel double sampling technique for ΔΣM´s that is insensitive to the path gain mismatch is presented. This technique uses a bilinear double sampling integrator in the first stage, achieving a first order shaping of the path gain mismatch error. Simulation results have been provided to verify the proposed technique