Mixed-Signal Testing

Abstract

The cost to produce mixed-signal devices is being dominated by their analog test costs. Today, the cost to test the analog portion of a mixed-signal device can be as high as 50% of the total cost. While the benefits of new market opportunities generally offset these costs, it is the general trend that has the mixed-signal device manufacturer concerned. As the rate of introduction of new technologies seems to favor the digital portion of the mixed-signal device, it would seem that in the next few years the cost associated with manufacturing a mixed-signal device will be almost entirely due to the cost of the analog tests. This situation is depicted in Fig. 2-1 through the use of two pie charts. The pie chart on the left-hand side attempts to capture the break down of production costs associated with a mixed-signal IC whereas the pie chart on the right projects these test costs into the future based on current trends. Clearly, the future situation appears quite grim. A product, even after succeeding in establishing itself on the market, will not persist and survive in the long run unless its performance and cost effectiveness remains competitive relative to other ICs. It is therefore readily apparent to electronic manufacturers today that the cost of test for the analog portion of the mixed-signal device can no longer be ignored, as the eventual market winners will be those products that contribute to the lowest overall test cost. It has also been claimed that improved product testability can aid in getting a product to the market place faster even though the design cycle is prolonged. This is largely a result of improved diagnostic capability.