A new LFSR based high-frequency test method for RSFQ circuit

Rapid single flux quantum (RSFQ) circuits have the advantages of high speed and low power consumption. The typical frequency of the RSFQ circuits is tens of GHz. Therefore, it is necessary to reliably test the high frequency performance of RSFQ circuits simply and effectively. This paper proposes a new on-chip high frequency testing method, which uses pseudo-random sequences generated by linear feedback shift register (LFSR) as the test vectors, and the output shift registers (SRs) to store the last piece of high-frequency testing result and read out it at low-frequency. Unlike the traditional high-frequency demonstration method of using the Input/Output SRs, our testing system can automatically generate a large number of test vectors to test the circuit at high frequency at low cost, making the whole high-frequency demonstration more reliable and con-vincing. On the other hand, this method is also a feasible and straightforward on-chip high-frequency test method for various RSFQ circuits. This work verified the proposed method, and the highest test frequency can reach 54 GHz while the circuit shows good operating margins.