Sanyo Electric Co., Ltd.

Takayuki Ohashi

Kazuhiro Kimura

Toshiyuki Ozawa

Akira Yamazaki

Hiroyoshi Kaneyama

For frequency change, the VCO is controlled through a sub-charge pump circuit to make a determination as to whether or not a difference of dividing data between before and after the change is within a predetermined range. When it is determined that the difference is outside the predetermined range, the loop filer is forcibly charged in a charge time which is determined proportional to the difference in the dividing data, to thereby control an oscillation frequency of the VOC. A large VOC oscillation frequency change can be swiftly realized. Also, while the frequency change circuit is controlling the oscillation frequency, a time constant of the loop filter in the PLL circuit is preferably set at a small value, so that frequency change by the frequency change circuit can be swiftly achieved.

Growing community of inventors

Ora-gun, Japan

Takayuki Ohashi