Summary: We have developed a GaAs direct-conversion π/4 shifted QPSK modulator IC equipped with variable attenuators for controlling the output power level of the 1.9 GHz Personal Handy Phone system in Japan (PHS). The IC was successfully demonstrated showing state-of-the-art performance with the image rejection ratio of more than 36 dBc at a low input power of -10 dBm in 1.9 GHz frequency range. By using the "Gate Current Control method by Pull-down FET's" (GCCPF), the equipped attenuators vary the output power from 0 dB to -28 dB by 4 dB step. The IC operates at a 2.7 V supply with power dissipation of 259 mW. The 2.64.6 mm2 chip with about 400 elements was fabricated by a 0.5 µm WNx-gate BPLDD GaAs MESFET process.