In this paper, analysis of a novel class of A/D converters based on asynchronous delta modulation (DM) is presented and a high level model is realized for the same. Using the high level model, analytical expressions are derived for the calculation of the inband signal-to-quantization noise ratio (SQNR) for the case of sinusoidal inputs and two-tone inputs. For the special case of sinusoidal inputs, an empirical formula is also derived for calculating the inband SQNR. The derived analytical and empirical expressions are verified using high level simulations and the simulation results are presented finally.