Twin-junction SIS mixer with an inductance made of a coplanar stripline

We propose to use a coplanar waveguide as an inductance instead of the micro-stripline in the parallel-connected twin-junction SIS mixer to achieve an ideal tuning bandwidth which is determined by the inverse of the /spl omega/R/sub N/C/sub J/ product of the twin-junction circuit. We have designed and made a parallel-connected twin-junction SIS mixer employing an inductance made of a coplanar waveguide at 100 GHz band. The resonance frequencies of the parallel-connected twin-junction device and its scaled devices are in fairly good agreement with the expected resonance frequencies. The performance of the parallel-connected twin-junction mixer with an inductance made of the coplanar waveguide is as good as those of conventional SIS mixers. This result suggests that the parallel-connected twin-junction SIS mixer employing the coplanar waveguide is one of the most promising candidates for fixed-tuned (or tunerless) SIS mixers.