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United States Patent | 6,259,289 |
Klemmer | July 10, 2001 |
A phase-locked loop circuit having improved phase noise characteristics includes a voltage-controlled oscillator developing an oscillating output signal responsive to a voltage control input. A reference source provides a reference frequency signal. A phase detector is operatively connected to the voltage-controlled oscillator and the reference source developing an output proportional to a phase difference between the oscillating output signal and the reference frequency signal. A loop filter connects the phase detector output to the voltage control input. The loop filter includes a switched-capacitor equivalent resistor.
Inventors: | Klemmer; Nikolaus (Apex, NC) |
Assignee: | Ericsson Inc. (Research Triangle Park, NC) |
Appl. No.: | 410308 |
Filed: | October 1, 1999 |
Intern'l Class: | H03L 007/06 |
Field of Search: | 327/141,147,148,150,155,157,159 331/17 375/374-376 |
5774023 | Jun., 1998 | Irwin | 327/157. |
5942949 | Aug., 1999 | Wilson et al. | 327/157. |
5963099 | Oct., 1999 | Nagoya et al. | 331/17. |