Clock Tree 101
By Linda Lua, Silicon Labs
What is a Clock Tree?
A clock tree is a clock distribution network within a system or hardware design. It
includes the clocking circuitry and devices from clock source to destination.
The complexity of the clock tree and the number of clocking components used
depends on the hardware design. Since systems can have several ICs with different
clock performance requirements and frequencies, a "clock tree" refers to the various
clocks feeding those ICs.
It's often the case that a single reference clock will be cascaded and synthesized into
many different output clocks, resulting in a diagram that looks a bit like a sideways
tree trunk. The "trunk" is the reference clock and the "branches" are the various
output clocks.

Fig.1 - Example "Clock Tree"