Apparatus for reducing spurious frequency components in the output signal of a direct digital synthesizer
US5291428A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 2, 1993 |
| Grant date | Mar 1, 1994 |
| Priority date | — |
| Expiry date | Mar 2, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2211/902
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Spurious frequency components from the output signal of a direct digital synthesizer are reduced with minimum degradation of the fundamental frequency of the output signal. The synthesizer has a phase accumulator for receiving digital multibit modulation data words from a source, a periodic wave function converter for converting the modulation data words into digital waveform data words and a digital-to-analog converter for converting the digital waveform data words into an analog signal which serves as the output signal. The output signal has a frequency and waveform dictated by the modulation data words. Reduction of spurious frequency components is achieved by generating a dither waveform representing a band limited waveform. The dither waveform is summed with the modulation data words prior to application to the wave function converter to provide a dither modulated analog output signal. A sampled dither signal is combined with the dither modulated analog output signal in such a manner that the dither waveform is cancelled from the fundamental waveform of the analog output signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.