Patent ID: 7907017

Claim:
A signal processing device, comprising: a voltage-controlled oscillator that controls a frequency of an output signal according to a voltage of an input signal; a loop divider that divides a frequency of a signal obtained based on the output signal by N (N is a real number, and is equal to or greater than one); a reference frequency divider that divides a frequency of a reference signal by R (R is a real number, and is equal to or greater than one); a phase comparator that outputs a signal according to a difference in phase between an output of said loop divider and an output of said reference frequency divider; a low-pass filter that passes a low frequency component, and supplies said voltage-controlled oscillator with the low frequency component; a difference outputter that outputs a difference between a voltage of the input signal, which is to be supplied to said voltage-controlled oscillator so that the frequency of the output signal coincides with a target value, and an output of the low-pass filter; and a switch that supplies said low-pass filter with an output of said phase comparator or an output of said difference outputter, wherein the input signal supplied to the difference outputter is supplied by a voltage target value recorder and has a same target voltage as the target voltage of the input signal supplied to the voltage-controlled oscillator.