A high power 490~530 GHz monolithic integrated frequency tripler is demonstrated based on Gallium Arsenide material. Based on the proposed symmetrical and balanced configuration, the tripler could not only achieve good amplitude and phase balances for efficient power synthesis, but also provide a DC bias path without any bypass capacitor to ensure efficient frequency doubling efficiency. Tolerance simulations are also carried out to analyze the effects of key electrical and structural parameters of the diode on the frequency doubling performance in order to maximize the frequency doubling performance. Finally, the developed 510GHz triplet, driven by approximately 80~200 mW input power, has an output power of 4~16 mW in the frequency range of 490~530GHz, where the peak frequency doubling efficiency is 11%. At the 522GHz frequency point, the triplex produces a maximum output power of 16mW driven by an input power of 218mW. The triplexer will later be used as the local oscillator source for a 1 THz solid-state external super outlier mixer.