Recently a novel clock distribution scheme called Branch-and-Combine(BaC) has been proposed. The scheme
guarantees constant skew bound irrespective of the size of the clocked network. It utilizes simple nodes to process
clock signals such that clock paths are adaptively selected to guarantee constant skew bound. The paper uses a
VLSI model to compare the properties of the new scheme to those of the well established H-Tree approach. The
H-Tree is a binary tree of simple buffers which is laid out such that leaves are at equal distances from the root.
Our study considers clocking 2-D processor meshes of arbitrary sizes. We evaluate and compare the relevant
parameters of both schemes in a VLSI layout context. We utilize parameters such as clock skew, link costs, node
costs and area efficiency as the basis for comparison. We show that for each BaC network, there is a certain
threshold size after which it outperforms the corresponding tree network in terms of skew. We also show that
except for node costs, BaC networks outperform the H-Tree, especially when the size of the clocked network is
large. As an extension we show that BaC clocking does not suffer from potential pulse disappearance, no matter
how large the network is.
Injection-Locked Clocking: A New GHz Clock Distribution Scheme
