US Patent 7933942 Low cost, high purity sign wave generator

An automatic test system that includes low cost and accurate circuitry for generating sinusoidal signals. Each sinusoidal signal generator produces a series of digital values approximating a sine wave. These values are computed, avoiding the need for large memories to store tables representing sine waves. Inaccuracies in the representation of the sine waves do not impact the accuracy of the resultant sine wave because circuitry used to correct for non-linearity errors in a digital-to-analog converter is programmed to also correct for errors introduced by approximating a sine wave with a computed function. A simple parabolic function may be used to compute approximations of a sine wave.