Just a few comments re FPGA's:
1) I thought everybody was glad that LSI was on their way out of the gate array business. I don't see offering a gate array on an ASIC as that much of an advantage over a designed-from-the-ground-up ASIC. In fact what is the purpose of an FPGA on an ASIC at all? If it's for debugging, ASIC's typically include a number of spare logic gates which can be connected using focused ion beam modification for a quick design debug turnaround.
2) The advantage of a programmable gate array is its quick turn--no need to wait weeks for the fab to turn your wafers. Also, no need to waste design resources on the silicon, just design the circuit. Its disadvantage is that the design is inefficient (in space on the silicon, which increases costs, and possibly in circuit design, which reduces performance). But, as Lu, said, it is ideal for low-volume and short-life-cycle products.
3) The advantage of an ASIC is that the circuit is optimized for the fab process and the layout on the die is as compact as it can get. There are costs up front for this (engineering resource costs, time costs), but the long-term cost and performance are maximized. The ASIC is ideal for high-volume and long-life-cycle products.
4) The only advantage I can think of for an FPGA/ASIC mix would be if you wanted to port a design block from an FPGA product into your ASIC without doing any new design work on the block. However, that kinda defeats the purpose of an ASIC, which is optimizing the design the first time around to get the payoff in the long run.
Regards,
G.P. |
