Direct frequency synthesizer
US4791377A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 20, 1987 |
| Grant date | Dec 13, 1988 |
| Priority date | — |
| Expiry date | Oct 20, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B2200/0072
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A frequency synthesizer has in series a digital synthesizer, mix and divide circuits, and a mix only circuit. Each mix and divide circuit includes a mixer having an IF input, a LO input and a RF output, a filter, and a frequency divider. A segment of a digital word selects a tone from a tone generator and also selects a passband of the filter. The selected tone is coupled to the LO input of the mixer. The frequency divider divides the filtered RF output of the mixer. The mix only circuit is at the output of the last of the series connected mix and divide circuits. The mix only circuit is similar to a mix and divide circuit, but does not have a frequency divider. The digital synthesizer provides a signal to the input of the first of the series connected mix and divide circuits, the frequency of which corresponds to a segment of a digital word. The filter is preferably a voltage tunable bandpass filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.