We explore the capacity of sub-Nyquist sampled analog channels based on modulation and filter bank sampling techniques. In particular, we derive the capacity of sampled analog channels under sampling via modulation banks and filter banks. A connection between these sampling mechanisms and MIMO Gaussian channels is illuminated. For sampling with a single branch of modulation and filtering, we identify the modulation sequence that optimizes capacity. These results illustrate the importance of the sampling technique on the capacity of sampled analog channels for a broad class of nonuniform sampling structures.