Direct interpolation method for reducing the non-linearity and quantisation distortion of analogue-to-digital convertors

A direct interpolation method is described that reduces the distortion due to quantisation and linearity errors of practical analogue-to-digital convertors. In contrast with other interpolation systems, the analogue signal is not oversampled, and no feedback loops are required. Compared with the conventional use of `dither´, direct interpolation provides an increase in signal-to-noise ratio as well as a reduction in harmonic distortion. Computer simulations and experimental measurements are presented. The method is particularly suited to reducing high-order harmonics and increasing the effective resolution of an ADC