Methods and apparatus for analog-to-digital conversion
US4758821A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 12, 1987 |
| Grant date | Jul 19, 1988 |
| Priority date | — |
| Expiry date | Jan 12, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M1/60
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An analog-digital converter includes a source of high frequency pulses comprising a variable frequency oscillator having an output frequency f which is a function of an analog condition. Also included is a source of a reference signal, preferably pulses, having a fixed frequency whose value is a fraction of the value of the frequency of the variable frequency oscillator. The first named souce also includes a counter-divider to which the output of the variable frequency oscillator is applied. The counter-divider has an output which is either f/N or f/N-M where N and M are whole integers and M is less than N. A phase comparator is responsive to the reference signal and to the output from the counter-divider for measuring the phase difference between the reference signal and the output pulses from the counter-divider. The dividing ratio of the counter-divider is under control of means responsive to the measure of phase difference such that the counter-divider is adjusted to bring the pulses from the counter-divider toward an in-phase relationship with the reference signal as seen at the phase comparator. The selection of the dividing ratio is carried out by a logic means which respond…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.