Why are FPGAs so expensive?
FPGA chips include both logic and programmable connections between logic elements, while ASICs include only the logic.

You'd be amazed at how much chip area is devoted to the "connection fabric" in an FPGA &mdash; it's easily 90% or more of the chip. This means that FPGAs use at least 10&times; the chip area of an equivalent ASIC, and chip area is expensive!

It costs a certain amount to do all of the processing on a given silicon wafer, no matter how many individual chips are on it. Therefore, to a first approximation, the chip cost is directly proportional to its area. However, there are several factors that make it worse than that. First, larger chips mean that there are fewer usable sites on the wafer to begin with &mdash; wafers are round, chips are square, and a lot of area is lost around the edges. And defect densities tend to be constant across the wafer, which means that the probability of getting a chip without a defect (i.e., "yield") goes down with chip size.