An active frequency tripler MMIC achieving an output frequency of 330 GHz is presented. With the use of integrated post- amplification the frequency tripler generates an average output power of −0.4 dBm in the output frequency range from 255 to 330 GHz, corresponding to an absolute bandwidth of 75 GHz. At 288 GHz the measured output power is 0.6 dBm with an input power of 10 dBm and with an input power of 1 dBm the conversion gain is −2.7 dB. The MMIC is realized in a metamorphic HEMT technology with 35 nm gate-length and uses 1.25 × 0.5 mm2 of chip space for convenient integration into multifunctional MMIC circuits.