| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a PLL circuit in which stability and responsiveness are enhanced while ensuring low voltage operation and a wide oscillation range. <P>SOLUTION: An output signal of a phase comparator that received a frequency signal formed on the basis of an oscillation signal of a current controlled oscillator and a reference signal is made into DC by a loop filter, a first current included in a control current of the current controlled oscillator is formed by a voltage/current converter to configure a PLL, and a calibration circuit is provided to change a self-oscillation frequency of the current controlled oscillator in accordance with the reference signal. A plurality of different reference voltages are then supplied to one input of each of a plurality of differential amplifiers as the voltage/current converter, an output voltage formed by the loop filter is supplied to the other input of each of the plurality of differential amplifiers, and output currents of the plurality of differential amplifiers are composed by a first current mirror path to form the first current. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
