Based on the GaAs process of Nanjing electronic devices institute, a 750-1100 GHz tripler and a low loss subharmonic mixer with center frequency of 1030 GHz have been independently 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 3μm thick monolithic circuit is supported in the cavity structure through beam lead. The measured result shows that the output power of the broadband frequency multiplier is -23 ~ -11 dBm in the frequency range of 790~1100 GHz. Using the above frequency multiplier source as the RF signal to test the subharmonic mixer, the conversion loss is better than 17.5 dB in the frequency range of 1020 ~ 1044 GHz, and the minimum conversion loss measured at 1030 GHz is 14.5 dB.