Low-noise frequency synthesizer
US5789987A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 22, 1996 |
| Grant date | Aug 4, 1998 |
| Priority date | — |
| Expiry date | Jan 22, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/093
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A frequency synthesizer (100) is utilized for producing an output signal (124) which is phase locked to a reference signal (110) operating at a reference frequency. The frequency synthesizer (100) comprises a main phase lock loop (PLL) (102), and a tracker PLL (128). The main PLL (102) includes a phase detector (112), two frequency dividers (108, 126), a loop filter (116), a notch filter (118), and a controlled oscillator (122). The tracker PLL (128) phase locks to the reference signal (110), and biases the notch filter (118) in order to maintain an accurate lock on the notch frequency which is proportional to the reference frequency. All circuits are integrated in the same monolithic device in order to track parametric tolerances such as transconductances of the operational transconductance devices included in the tracker PLL (128) and the notch filter (118).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.