Patent ID: 8659331

Claim:
A frequency generator, comprising: a phase accumulator configured to generate a phase signal representing a phase angle; and a sin-cos converter configured to receive the phase signal as a phase input, and generate a sin-cos curve value as a converter output, the sin-cos curve value approximately equal to a sin-cos value at the phase angle within a predefined tolerance; and the sin-cos converter, comprising: a point lookup table comprised of main sin-cos endpoints at predefined intervals in a first angle range, each of the main sin-cos endpoints comprising the sin-cos curve value at a given angle among the predefined intervals; a correction lookup table comprised of a plurality of correction values representing a difference between first sub-main sin-cos endpoints at the predefined intervals in a second angle range between two associated main sin-cos endpoints in the point lookup table and approximations of the sin-cos curve values at given angles among the predefined intervals; a point selection circuit configured to provide from the point lookup table, a first main sin-cos endpoint associated with a first side of the phase angle and a second main sin-cos endpoint associated with a second side of the phase angle; a correction selection circuit configured to provide from the correction lookup table, a first correction value correlated with the first main sin-cos endpoint and a second correction value correlated with the second main sin-cos endpoint; and a converter circuit configured to provide the sin-cos curve value at the phase angle in a converter output signal based on the first and second main sin-cos endpoints and the first and second correction values.