All FPGAs contain some type of
. The structure and complexity of the interconnect is largely determined by the programming technology and the architecture of the basic logic cell. The raw material that we have to work with in building the interconnect is aluminum-based metallization, which has a sheet resistance of approximately 50 m
/square and a line capacitance of 0.2 pFcm
. The first programmable ASICs were constructed using two layers of metal; newer programmable ASICs use three or more layers of metal interconnect.
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