220 GHz wideband integrated receiver front end based on planar Schottky diodes

In this article, a 220 GHz wideband receiver front end is proposed, featuring a 220 GHz subharmonic mixer and a 110 GHz wideband tripler integrated in one single block. The 220 GHz subharmonic mixer and 110 GHz tripler are firstly developed separately with proper planar Schottky diodes. According to the simulated and experimental results, the direct combination of independent mixer and tripler will lead to deterioration of the front end's performances, especially for wideband receivers. This indicates the necessity of building matching network between the cascade circuits in wideband submillimeter receivers. To improve the integral performances of the receiver front end and reduce its size, the combination of the subharmonic mixer and the tripler was optimized with load-pull techniques and realized in one block. Measured results reveal that the single sideband (SSB) conversion loss of the integrated receiver front end is 7.5-11 dB from 185 to 250 GHz, while the double sideband (DSB) noise temperature is 750-1600 K within this frequency range. The integrated front end features half size of the combination of independent modules and better performances. Good agreement between the simulated and measured results shows that the integration and optimization techniques can be applied to realize compact terahertz systems in the future.