Patent attributes
An automatic test system that includes low cost and accurate circuitry for generating sinusoidal signals. Each sinusoidal signal generator includes a look-up table that can, for each phase on sine wave, output two digital values representing an in-phase and a quadrature-phase value of the sine wave. Simple circuitry can be used to address the look-up table to output in-phase and quadrature-phase values. The in-phase and quadrature-phase values can be applied to down-stream circuitry, such as error correction circuitry, that uses an in-phase and a quadrature-phase value to process the sine wave without the need for a relatively complex phase shifter in the down-stream circuitry. A dual-port memory may be used to implement the look-up table so that both an in-phase and a quadrature-phase value may be obtained from a single block of memory that stores a representation of a sine wave.
