Title:
PLL周波数シンセサイザ回路
Document Type and Number:
Japanese Patent JP4446568
Kind Code:
B2
Abstract:
A voltage-controlled oscillator outputs a signal of a frequency controlled by a voltage of an input signal, the output signal being used for feedback as an internal change signal. A phase comparator detects a phase difference between the internal change signal and an external reference signal. A charge pump outputs the signal having the voltage based on the phase difference to the voltage-controlled oscillator via a low-pass filter. The charge pump is controlled so that the voltage of the signal input to voltage-controlled oscillator becomes a voltage for oscillating a lock frequency. When instruction of changing the lock frequency is input, and/or a phase inversion of the internal change signal used for feedback in a locking-up operation rendered in response to the instructions is detected, a control is made such that an absolute value of an output current of the charge pump is increased.
Inventors:
Hiroto Nakamichi
Application Number:
JP2000221087A
Publication Date:
April 07, 2010
Filing Date:
July 21, 2000
Export Citation:
Assignee:
Fujitsu Microelectronics Limited
International Classes:
H03L7/093; H03L7/089; H03L7/107; H03L7/183
Domestic Patent References:
| JP11284508A | ||||
| JP6112817A | ||||
| JP9116430A | ||||
| JP4227332A |
Attorney, Agent or Firm:
Yasuo Hirai