Towards a THz Sideband Separating Subharmonic Schottky Mixer

Paper in proceeding, 2008

GaAs Schottky mixers with state of the art planar submicron diodes are used for THz-detection up to 3 THz today [1]. GaAs Schottky diodes can operate in room temperature which makes them good candidates for space applications and an interesting low cost alternative to low noise cryogenic SIS and HEB technologies. The main advantage of a sideband separation scheme besides that the lower and upper sidebands are indeed separated, is that the IF bandwidth is increased by a factor of two. Moreover, there is no need for image rejection filters on the RF input, which can be bulky and increase the weight and cost of the overall receiver system. Sideband separation mixers have been implemented at THz frequencies before [2], however up to this point they have never been tried with Schottky diodes in a subharmonic mixer configuration. We will present the current status of the development of a novel sideband separating subharmonic reciever topology operating at 340 GHz, see Fig1. The design of a subharmonic mixer and the LO and RF waveguide hybrids will be presented followed by an account of measured results of the individual components.