Bit-Error-Rate Measurements of RSFQ Shift Register Memories

Error rates of rapid-single-flux-quantum (RSFQ) shift register memories were investigated using a high-speed error-rate measurement system in order to demonstrate their reliability and stability. We designed and implemented an 8 times 8-bit shift register memory using the CONNECT cell library and the SRL 2.5 kA/cm
²
Nb process. The total number of Josephson junctions including the test system is 4184, and the circuit area is 2.1 mm times 3.2 mm. We measured the error rates of every storage node by reading out the data 2
¹⁶
times at the clock frequency of 16 GHz. The measured error rates were lower than 10
^-10
with DC bias margin better than plusmn5%.