A highly integrated quasi-millimeter-wave transmitter MMIC that integrates 26 circuits in a 3 mm x 3 mm area using three-dimensional MMIC (3D-MMIC) technology is presented. The power dissipation of the MMIC is only 0.54 W. It achieved a high P1dB of 6 dBm and gain of 19 dB at 26 GHz. Furthermore, it integrated step attenuators with a new built-in inverter using an N-channel depression FET for transmit power control.