Method and apparatus for spur-reduced digital sinusoid synthesis
US5459680A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 20, 1993 |
| Grant date | Oct 17, 1995 |
| Priority date | — |
| Expiry date | Oct 20, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2211/902
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A technique for reducing the spurious signal content in digital sinusoid synthesis. Spur reduction is accomplished through dithering both amplitude and phase values prior to word-length reduction. The analytical approach developed for analog quantization is used to produce new bounds on spur performance in these dithered systems. Amplitude dithering allows output word-length reduction without introducing additional spurs. Effects of periodic dither similar to that produced by pseudo-noise (PN) generator are analyzed. This phase dithering method provides a spur reduction of 6(M+1) dB per phase bit when the dither consists of M uniform variates. While the spur reduction is at the expense of an increase in system noise, the noise power can be made white, making the power spectral density small. This technique permits the use of a smaller number of phase bits addressing sinusoid look-up tables, resulting in an exponential decrease in system complexity. Amplitude dithering allows the use of less complicated multipliers and narrower data paths in purely digital applications, as well as the use of coarse-resolution, highly-linear digital-to-analog converters (DACs) to obtain spur performa…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.