A new model is introduced for timing jitter in the analog-to-digital conversion process. In contrast with the well- known classical model, the proposed model takes into account the interaction between quantization and jitter. This is of special relevance when quantization plays a significant role, i.e., in the case of a low-resolution analog-to-digital converter. It is shown that the use of the classical model provides an increasing underestimate of jitter frequency-domain effects as the signal amplitude decreases, whereas such effects are properly predicted by the proposed model. Moreover, the sinusoidal waveform as well as multisine waveforms can be treated by the new model.