A Nb ground plane extends over most of the upper side of the substrate, and has gold contact pads along all four sides. These pads contact the mixer block through gold crush-wires which are compressed as the block is assembled. The image separating mixer, showing the signal and LO waveguides, suspended stripline coupling probes, and the main substrate. All conductors are on the same side of the substrate and the energy is confined to a region close to the center conductor, which allows the use of a conveniently thick substrate. The periodic bridges are grounded at their ends, which effectively suppress coupling to the odd-mode which can occur in long CPW lines, and reduces coupling between adjacent components.
Dimensions are in microns.
A detailed view of the mixer substrate is shown in Fig. 4. It is divided in the quadrature hybrid and passes into the mixers via the LO couplers. Substrate of the sideband separating mixer, showing the main components. Most of the surface is covered by a ground plane. All photolithography was performed with a 5x i-line wafer stepper.