Rapid Single-Flux-Quantum Circuit Routing Algorithm Considering Length Matching

The high frequency characteristics of rapid single-flux-quantum (RSFQ) circuits poses a great challenge to circuit layout design. In order to solve the circuit delay problem caused by the high frequency characteristics of RSFQ, delay elements such as passive transmission line can be used in the routing stage. The delay of a passive transmission line is roughly proportional to its length, and the power consumption of the passive transmission line does not increase with the increase of the wirelength, so length matching routing is a crucial problem for RSFQ circuits. Therefore, we propose an efficient RSFQ circuit routing algorithm considering length matching, including the following key strategies: 1) when generating the initial path, a method of detour routing is presented to meet the partial length matching of passive transmission lines without changing the initial routing space; 2) an iterative resource insertion algorithm based on region-awareness is utilized to reduce the area of additional resources needed to be added; 3) a length-matching driven routing algorithm considering blocking cost is designed, which improves the resource utilization of routing space. Experimental results show that, compared with existing multi-terminal routing algorithms, the proposed algorithm reduces the area required for routing by 8% and the running time by 36%, thus achieving fast and high-quality routing results.