Modulator

A modulator, and more particularly an HPSK modulator, is disclosed that enables the circuit scale to be reduced and also enables power consumption to be reduced. An HPSK modulator 209 incorporated in a radio communication apparatus or the like is equipped with a spreading code multiplication section 11, a complex arithmetic section 101, a coefficient determination section 51, and raised COS filters 41 and 42. Spreading code multiplication section 11 multiplies transmit data DPDCH1 by a spreading code Cd1. Complex arithmetic section 101 performs complex arithmetic on an output signal output from spreading code multiplication section 11 and a scrambling code Sn, and performs conversion to complex data. Coefficient determination section 51 determines a filter coefficient Ad1n based on a gain factor d1 that determines transmission power. Raised COS filters 41 and 42 band-limit the complex data using the filter coefficient.