Modulator and frequency multiplier for use therein

Abstract

A modulator that effectively suppresses carrier leakage is disclosed. The modulator includes a frequency multiplier, a phase shifter and an orthogonal modulator. The frequency multiplier outputs complementary signals whose frequencies are twice the frequency of a first carrier signal. The phase shifter divides the frequencies of the output signals of the frequency multiplier to produce a plurality of second carrier signals whose phases are shifted by 90 degrees from one another. The orthogonal modulator receives an input signal and the second carrier signals from the phase shifter and outputs signals obtained by combining the input signal with the second carrier signals. The frequency multiplier has an input circuit section including a differential circuit. The differential input section receives complementary signals as the first carrier signal. The orthogonal modulator has an output circuit section including a differential circuit.