Modulator

n 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 incorporated in a radio communication apparatus or the like is equipped with a spreading code multiplication section , a complex arithmetic section , a coefficient determination section , and raised COS filters and . Spreading code multiplication section multiplies transmit data DPDCH by a spreading code Cd. Complex arithmetic section performs complex arithmetic on an output signal output from spreading code multiplication section and a scrambling code Sn, and performs conversion to complex data. Coefficient determination section determines a filter coefficient Adbased on a gain factor βd that determines transmission power. Raised COS filters and band-limit the complex data using the filter coefficient.