Patent ID: 7839230
Filing Date: 2010-11-23
Classification: H03C,H03L

Abstract:
1. A PLL oscillation circuit which includes a reference frequency oscillator, a phase comparator, a loop filter, and a voltage-controlled oscillator; the PLL oscillation circuit comprising: a PM-PM table that is utilized for compensating a nonlinearity of the voltage-controlled oscillator; a variable current source connected in between the voltage-controlled oscillator and a supply potential terminal; an amplitude detector that detects an output amplitude of the voltage-controlled oscillator; an amplitude controller that controls a current value of the variable current source so as to have the output amplitude of the voltage-controlled oscillator detected by the amplitude detector to be a desired amplitude; a LPF connected in between the amplitude controller and the variable current source; and a switch that connects or disconnects the LPF between the amplitude controller and the variable current source, and when switching an output frequency of the voltage-controlled oscillator, a connection of the switch is turned on, so as to connect the amplitude controller to the variable current source through the switch, and to update a setting value in the PM-PM table to be a value that corresponds to an output frequency after the switching, and when the voltage-controlled oscillator outputs a desired frequency signal, the connection of the switch is turned off and the amplitude controller is connected to the variable current source through the LPF.