RSFQ impulse logic circuitry for future applications in high frequency metrology

Abstract

At PTB, at a level of medium complexity in superconductor–insulator–superconductor (SIS) technology, rapid single flux quantum (RSFQ) circuits can be fabricated with a high degree of reproducibility. Their functionality has been proven up to frequencies higher than 40 GHz. The reliability of circuit operation has been demonstrated by bit error rates of about 10 −16. On this basis, the RSFQ impulse logic opens up a wide field of digital applications in high frequency (HF) metrology. A unique feature to utilize for the evaluation of microwave systems and equipment is the ability of direct digitizing of HF signals. Three attractive examples are discussed to apply in the fields of Josephson voltage standards (JVSs) and microwave noise power. With regard to future requirements to operate RSFQ circuits at higher integration levels, the possibility of an implementation of intrinsically shunted tunnel junctions as the active circuit elements using superconductor–insulator–normal conductor–insulator–superconductor (SINIS) technology is discussed.