Civil Engineering Reference
In-Depth Information
where is the sheet resistance‚ which is the ratio of the resistivity of the
material and the thickness of the wire. A simple model for the line-to-ground
wire capacitance is given by
where is the area capacitance and is the fringing capacitance. The line-to-
line capacitance for between two wires that have a coupling length of
and a
separation of
may be characterized by
where is the coupling capacitance per unit length‚ and is an empirical
constant whose value is between 1 and 2 (a frequently-used value for is 1.34).
Other‚ more complex‚ models for the interconnect capacitance such as those
proposed by Sakurai [ST83] and Chern [ ]‚ are frequently employed.
An on-chip wire with a ground plane is most accurately represented as a
distributed transmission line‚ with infinitesimal elements of size with a
resistance of and a capacitance to ground of where and are
the per unit resistance and capacitance‚ respectively. However‚ practically‚ this
may be represented by discrete‚ noninfinitesimal segments with lengths of the
order of a hundred microns‚ each associated with lumped elements in the form
