Patent ID: 7889812

Claim:
A direct digital frequency synthesizer comprising: a first memory for storing a plurality of digitized samples of a first portion of a sinusoidal waveform; a second memory for storing a plurality of digitized samples of a second portion of said sinusoidal waveform, wherein said first and second portions of said sinusoidal waveform together define a predetermined fraction of a whole cycle of said sinusoidal waveform; a first extra memory for storing a plurality of extra digitized samples of said sinusoidal waveform beyond said first portion; a second extra memory for storing a plurality of extra digitized samples of said sinusoidal waveform beyond said second portion; and an access circuit having a first input for receiving a phase offset and responsive to said digitized samples from said first and second memories and to said digitized samples of said first and second extra memories for outputting cosine and sine waveforms offset from a quadrature relationship with respect to each other by said phase offset.