Arent Fox LLP
PLL frequency synthesizer
A frequency synthesizer includes a voltage-controlled oscillator, a frequency range tuning circuit which detects a frequency control code that sets a voltage-controlled frequency range of the voltage-controlled oscillator corresponding to the frequency division ratio which is variably-set, and a frequency control code memory which stores the frequency control code detected by the frequency range tuning circuit corresponding to the frequency division ratio. In an initialization interval, the frequency range tuning circuit detects the frequency control code corresponding to the frequency division ratio which is variably-set, and the frequency control code memory stores the frequency control code which is detected. In a normal operation interval, in response to the frequency selection signal, the frequency control code, which is stored in the frequency control code memory and corresponds to the frequency division ratio which is variably-set, is output to the voltage-controlled oscillator.
Fujitsu Limited
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inventional inventional inventional
Toshihiko Masafumi
Mori Kondou