Superconductive passive transmission lines (PTL) are widely used for signal routing in large-scale rapid single flux quantum (RSFQ) circuits. Due to the imperfect matching of the transmission lines between the driver and receiver, single flux quantum (SFQ) pulses are partially reflected. The round trip propagation time of these reflections can coincide with the following SFQ pulse, resulting in a decrease in bias margins or incorrect circuit behavior. This resonant effect depends upon the length of the PTL and the clock frequency of the signal. A methodology to reduce and manage this effect is the focus of this article. A closed-form expression describing the dependence of the resonance frequency on the length of the PTL is presented. This expression describes a set of forbidden lengths for PTL interconnect segments in RSFQ circuits. The proposed methodology and algorithm insert active PTL-based repeaters into long superconductive interconnect while ensuring the length of the line segment is outside the forbidden region and increasing bias margins.

中文翻译：

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SFQ 互连中的中继器插入

超导无源传输线 (PTL) 广泛用于大规模快速单通量量子 (RSFQ) 电路中的信号路由。由于驱动器和接收器之间传输线的不完美匹配，单通量量子 (SFQ) 脉冲被部分反射。这些反射的往返传播时间可能与随后的 SFQ 脉冲重合，导致偏置裕度降低或电路行为不正确。这种谐振效应取决于 PTL 的长度和信号的时钟频率。减少和管理这种影响的方法是本文的重点。给出了描述共振频率对 PTL 长度的依赖性的封闭式表达式。该表达式描述了 RSFQ 电路中 PTL 互连段的一组禁止长度。