Method and apparatus for direct digital frequency synthesizer
US5737253A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 30, 1995 |
| Grant date | Apr 7, 1998 |
| Priority date | — |
| Expiry date | Aug 30, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F1/0328
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The present invention comprises a direct digital frequency synthesizer. A phase accumulator provides a normalized angle .theta. to a sine/cosine generator that outputs the value of the sine/cosine function at the provided angle. The she/cosine generator in a preferred embodiment comprises a plurality of multiplierless butterfly and carry-save stages in cascade that perform angle rotations on a phasor on the unit circle whose x and y coordinates correspond to cosine and sine values. To calculate the sine and cosine values at a particular angle .theta.=b.sub.1 .theta..sub.1 +b.sub.2 .theta..sub.2 +. . . +b.sub.N .theta..sub.N where b.sub.k .epsilon. {0, 1} are the binary bits and the .theta..sub.k =2.sup.-k are the associated positional weights, each of the butterfly and carry-save stages rotate the phasor by an amount .theta..sub.k =2.sup.-k. The direction of the rotation, clockwise or counter-clockwise, depends upon the value of the binary bits b.sub.k. After undergoing all of the rotations, the phasor has x and y coordinates that approximate the desired cosine and sine values to a specified accuracy. In a preferred embodiment, the datapath of the present invention is multiplierles…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.