Modern analog placement techniques require consideration of current path and symmetry constraints. The symmetry pairs can be efficiently packed using the symmetry island configurations, but not all these configurations result in minimum gate interconnection, which can impact the overall circuit routing and performance. This article proposes the first work that reformulates this problem considering all of them together in the form of parallel current path (PCP) constraints. PCP constraints, in addition to monotonic current paths, also consider partial-monotonic current paths to generate a more compact placement. We use a novel two-step approach to detect symmetry-feasible sequence-pairs (SFSPs) without doing placement construction by using representative sequence-pair (RSP). Then a placement algorithm satisfying these constraints is formulated to reduce a vast search space via efficient sequence pair manipulation. The experimental results show that this formulation and algorithm can generate multiple placement solutions that satisfy all the constraints in a more tightly packed configuration, resulting in smaller wirelength, reduced parasitics, and thus better post-layout performance.

中文翻译：

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使用 PCP-SP 探索具有部分单调电流路径和对称约束的多个模拟布局


现代模拟布局技术需要考虑电流路径和对称性约束。使用对称岛配置可以有效地封装对称对，但并非所有这些配置都会产生最小的栅极互连，这可能会影响整体电路布线和性能。本文提出了第一个工作，以并行电流路径（PCP）约束的形式重新阐述了这个问题，将所有这些问题一起考虑。 PCP 约束除了单调电流路径外，还考虑部分单调电流路径以生成更紧凑的布局。我们使用一种新颖的两步方法来检测对称可行序列对（SFSP），而无需使用代表性序列对（RSP）进行布局构建。然后制定满足这些约束的放置算法，以通过有效的序列对操作来减少巨大的搜索空间。实验结果表明，该公式和算法可以生成多个布局解决方案，满足更紧密封装配置中的所有约束，从而缩短线长，减少寄生效应，从而获得更好的布局后性能。