Digital filter for phase-locked loop integrated circuits
US9236871B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 15, 2014 |
| Grant date | Jan 12, 2016 |
| Priority date | — |
| Expiry date | Aug 15, 2034 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/1974
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A digital filter for a frequency synthesizer (e.g., PLL, UFT) may include an analog-to-digital (ADC) converter, which is responsive to a control voltage at an input thereof, and a digital-to-analog (DAC) converter, which has an input responsive to a signal generated at an output of the ADC. An impedance element is provided between the DAC and ADC. The impedance element has real and reactive components, a first current carrying terminal electrically coupled to an output of the DAC and a second current carrying terminal electrically coupled to the input of the ADC. The impedance element can include a resistor and a capacitor, which are electrically connected in parallel. A gain device, such as a programmable multiplier, may also be provided, which has an input responsive to the signal generated at the output of the ADC and an output electrically coupled to the input of the DAC.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.