Patent ID: 7292118

Claim:
A modulator comprising: a PLL circuit which detects a phase difference between an input signal of which a frequency is divided and a reference signal; an AGC circuit which controls a gain of a modulating signal based on the input signal of which a frequency is divided, and which outputs a control signal; and a voltage controlled oscillation circuit which controls an oscillation frequency of a signal output from said PLL circuit based on said control signal, wherein said voltage controlled oscillation circuit includes a first voltage controlled reactance unit which has said signal output from said PLL circuit input thereto, a second voltage controlled reactance unit which has said control signal input thereto, and a high-frequency oscillation circuit connected in parallel with said first and second voltage controlled reactance units, which outputs said input signal, wherein the first voltage controlled reactance unit includes a first varactor diode and a second varactor diode, wherein cathodes of the first and second varactor diodes are connected to each other, and wherein the signal output from the PLL circuit is input to the cathodes.