Development of a rapid-single-flux-quantum shift register for applications in RF noise power metrology

Shift registers operated in digital feedback mode and utilized as pseudo random noise generators are very attractive for application as noise standards in rf noise power metrology. The paper reports on the concept of the integrated circuits required, based on superconducting Rapid-Single-Flux-Quantum (RSFQ) logic, and realized in Nb/Al/sub 2/O/sub 3/-Al/Nb technology. The design and layout of an 8-bit shift register is presented. Measurement results are reported which prove correct functionality for clock frequencies up to 45 GHz for standard operation. Typical bias current margins for operation of the shift register are /spl plusmn/27%. Further narrow-band limited ranges of operation have been found up to 60 GHz.