Low-frequency noise reduction in time-shared switched-capacitor ladder filters

By a proper use of the time-sharing technique in SC ladder filters, it is possible to reduce the output noise contributed by the time-shared operational amplifiers in the low-frequency region (1/f noise); generic analysis for the noise components, limited in the baseband, is given for time-shared networks with respect to the conventional ones. Practical design formulas are then derived for the active ladder structures, with some examples of allowable implementations to get the desired reduction of the 1/f noise contributions.