Based on the GaAs process of Nanjing electronic devices institute, a 750~1 100 GHz tripler and a low loss 1 030 GHz sub-harmonic mixer have been completed. To improve the performance of the module, the parameter optimization of the device is introduced in the traditional design method of field circuit combination, and the mutual feedback relationship is established. Therefore, the whole design process establishes the closed-loop. The 3 μm thick monolithic circuit is supported in the cavity structure by using beam lead. The measured result shows that the output power of the broadband frequency multiplier is -23 ~ -11 dBm in the frequency range of 790~1 100 GHz. Using the above-mentioned frequency multiplier source as the RF signal to test the sub-harmonic mixer, the conversion loss is better than 17.5 dB in the frequency range of 1 020 ~ 1 044 GHz, and the minimum conversion loss is 14.5 dB at 1 030 GHz.