A Compact 340 GHz 2x4 Patch Array with Integrated Subharmonic Gilber Core Mixer as a Building Block for Multi-Pixel Imaging Frontends

For linear multi-pixel imaging systems, a linear stack of pixels comprising of an antenna and a heterodyne receiver are needed. Such pixels can be realized using MMIC processes. The main constraint for such multi-pixel system is a compact array of pixels giving high coupling to quasi-optics used for focusing. This paper addresses this trade-off and presents a novel solution based on beam synthesis of two consecutive subarrays. One such sub-array along with heterodyne receiver is described as half-pixel in this paper and it is realized using 2×4 patch array and Gilbert core sub-harmonic mixer using a 250nm DHBT process. The patch array has ohmic loss better than 8 dB and mixer conversion loss is 6-8 dB over 320-350 GHz RF band. The chip size is 1mm × 2mm and therefore for 7 simultaneous beams a MMIC of 8 half-pixels is foreseen.