Magnitude scaling for increased SFDR in DDFS

Abstract

Abstract-When generating a sine table to be used in, e.g., frequency synthesis circuits, a widely used way to assign the table content is to simply take a sine wave with the desired amplitude and quantize it using rounding. This results in uncontrolled rounding of up to 0.5 LSB, causing some noise. In this paper we present a method for increasing the signal quality, simply by adjust the amplitude within a ±0.5 range from the intended. This will not affect the maximum value of the sinusoid, but can increase the spurious free dynamic range with some dB.