Title:
SEMICONDUCTOR INTEGRATED CIRCUIT
Document Type and Number:
Japanese Patent JP3294116
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To oscillate one voltage controlled oscillator(VCO) over wide frequency range.
SOLUTION: A frequency detection circuit 15 detects the frequency of horizontal synchronizing signal and generates a mode switching signal corresponding to the detected frequency. A VCO 13 consisting of a PLL circuit 16 has plural oscillation modes, for which the frequency of integer multiple of horizontal synchronizing signal is divided into plural frequency ranges, and oscillates the signals of respective frequency ranges corresponding to a control voltage outputted from a filter 12. The oscillation mode of this VCO 13 is switched corresponding to the mode switching signal outputted from the frequency detection circuit 15. Therefore, the frequencies of wide range can be oscillated by one VCO 13. Further, since the ranges of frequencies in respective oscillation modes of VCO 13 are narrow, oscillation gain can be suppressed low and the degradation of jitter characteristics can be prevented.
Inventors:
Good day Kawakami
Application Number:
JP25319196A
Publication Date:
June 24, 2002
Filing Date:
September 25, 1996
Export Citation:
Assignee:
Toshiba Corporation
International Classes:
H03L7/087; H03L7/099; H03L7/10; (IPC1-7): H03L7/10; H03L7/099
Domestic Patent References:
| JP6291651A | ||||
| JP3259619A | ||||
| JP774592A | ||||
| JP484567A |
Attorney, Agent or Firm:
Takehiko Suzue (6 outside)