Experimental verification of the pumping of SIS mixer with an distributed SIS frequency doubler

In this paper, we present the performance of the first frequency multiplier using the non-linearity of distributed SIS junctions. The prototype doubler based on distributed SIS junction was for the first time able to pump an SIS mixer. The multiplication efficiency of the distributed SIS junction is 15-30 % for a fractional bandwidth of 10% with excellent spectral line purity. The measured -3 dB line width of the multiplied signal is better than 1 Hz, which was limited by the resolution bandwidth of the spectrum analyzer. The results attained in this work show that the distributed SIS junction frequency multipliers have considerable future potential, and could possibly be used in LO source in single-end and multi-pixel SIS mixer receivers.