Patent ID: 7606849

Claim:
A method for generating a high purity reference signal with high frequency resolution, comprising: selecting N frequencies F 1 through FN to be generated in a pattern of frequencies that repeats with a period of duration T, and selecting N time durations T 1 through TN as the durations of F 1 though FN respectively during T such that T 1 +T 2 + . . . +TN=T and an absolute value of the largest frequency difference between any two of the frequencies F 1 though FN is at least two orders of magnitude less than π/T; selecting N frequency tuning words FTW 1 through FTWN representing a phase increment required at each clock period to generate F 1 through FN, respectively; switching between FTW 1 through FTWN for the durations T 1 through TN in the repeating pattern of frequencies; receiving the switched FTW 1 through FTWN and accumulating a total accumulated degree of phase at each clock period; and converting the total accumulated degree of phase to generate a representation of the high purity reference signal at each clock period.