The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 16, 1999
Filed:
Jun. 05, 1997
Hisashi Adachi, Osaka, JP;
Hiroaki Kosugi, Osaka, JP;
Tomoki Uwano, Osaka, JP;
Takeshi Miura, Kanagawa, JP;
Youichi Morinaga, Kanagawa, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A frequency synthesizer that can switch an output frequency fast and generates little spurious output is provided. This frequency synthesizer comprises a phase locked loop including a voltage-controlled oscillator, a high frequency divider, a phase frequency comparator and a low-pass filter. The divisor controller circuit supplies a divisor that varies cyclically to the high frequency divider for a fractional dividing operation. When switching the output frequency, a passing bandwidth of the low-pass filter is enlarged to widen a loop bandwidth of the phase locking loop for fast switching. After switching, the passing bandwidth of the low-pass filter is reduced to narrow the loop bandwidth for reduction of a spurious output, at the timing when a predetermined period has passed for the switched output frequency to stabilize substantially.