Direct digital frequency synthesizer using sigma-delta techniques
US5563535A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 29, 1994 |
| Grant date | Oct 8, 1996 |
| Priority date | — |
| Expiry date | Nov 29, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F1/0328
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A direct digital synthesizer (DDS) for generating a waveform generates a sequence of n-bit phase signals representing phase of the waveform, wherein n is an integer greater than zero. Each n-bit phase signal comprises a phase estimate signal and a phase error signal. The phase estimate signal comprises a most-significant m bits of the n-bit quantity (0 <m<n). The phase-error signal comprises a least-significant n-m bits of the n-bit quantity. The DDS further has a sigma-delta modulator for generating a compensation signal from the phase error signals. The phase estimate signal is added to the compensation signal to produce a compensated phase signal, which may be used to address a look-up table having waveform samples stored in correspondence with look-up table addresses. A digital to analog converter may be coupled to receive waveform samples from the look-up table in order to generate a corresponding analog waveform signal. In accordance with another aspect of the invention, an improved modulator includes the improved DDS as described above, for generating a stream of carrier signal samples; and a complex multiplier/accumulator (CMAC) for multiplying a stream of the carrier signa…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.