Tekmos' Blog

Field-Programmable Gate Arrays (FPGAs) are an excellent choice for rapid development, prototyping, and low-volume production. But as products mature and volumes increase, many organizations reach a tipping point were continuing with an FPGA is no longer the most efficient or cost-effective option.

So how do you know when it’s time to make the move?

Below are 7 clear signs that your design may be ready for FPGA-to-ASIC conversion and how making the transition can improve performance, reduce costs, and ensure long-term supply.

1. Your Production Volumes Are Increasing

FPGAs are ideal for low-to-medium volumes, but their per-unit cost remains relatively high compared to ASICs. If your production volumes are scaling into the thousands (or more), an ASIC can significantly reduce unit cost over time.  

Tekmos offers customers the ability to have their ASIC or customer specific designs created and manufactured in the United States. This is typically important for companies that require ITAR compliance in their market.

The ability to design a unique customer specific part can provide competitive advantages and exceptional protection of confidential intellectual property.

Tekmos performs all design work in our Austin, Texas technology lab.

We can then have masks created, wafers fabricated and assembled with our partners in their US facilities. Tekmos then tests every part in our Austin test facility before shipment to customers. A customer specific design is essential when the application requires functions that are not readily available from standard products or when IP must be protected under the ITAR compliance rules.

Tekmos can build a wide range of devices including microprocessors, digital, analog, extended voltage ranges and supports extended temperature from -55ºC to as high as 250ºC. Our engineers are very skilled at including existing IP already developed to provide a very fast lead-time for prototypes and production units.

Production ASIC technology nodes range from 16nm up to 600nm, and the 10nm and 7nm nodes are nearing production status. With each decreasing technology node, in rough terms, the NRE doubles, the logic density doubles, and the wafer cost increases by ~25%. Going to a more advanced note can result in a cost savings as long as the volume compensates for the increased NREs.

There are two items that work against migrating to a more advanced node. The first is the anticipated production volume. Economically speaking, this can be phrased as how many production parts does it take before the unit cost savings equals the increase in NRE, and how long will it take to reach the breakeven point?

How long it takes to reach that breakeven point is important. A node selection that breaks even in 5 years is not economical. A project that breaks even in a few months is a no-brainer. Typically, an ASIC node selection needs to breakeven in under a year, with a 6 to 9 month period being ideal.

A second point to consider is that an increase in logic density at a given node does not always result in a lower cost die. A die consists of core logic that is surrounded by a pad ring that consists of the input / output buffers, the power bussing, and the scribe line (the space required to allow the die to be cut from the wafer). The I/O buffers have a minimum size that is necessary to withstand ESD damage. The pads have a minimum size because of assembly constraints. And together, this produces a pad ring that does not change size with differing technologies.

Consider the case of a 256 pin circuit with a 50u pad pitch. This die will be a minimum of 3.5 mm / side, and have a core area of 6.25mm². This tables show how many gates can be put into that 6.25 mm² space. So if a design has less than 400,000 gates, and if the 180 nm node will support the speed requirements, then there is no reason to use a smaller technology node.

There are many technology nodes available today, ranging from the most advanced 16 nm up through 1 u. So which one should you use for your ASIC? The answer depends on a combination of circuit size, speed requirements, and production volumes.

The biggest downside for the advanced technology nodes is the cost of the masks necessary to fabricate the wafers. The mask cost tends to double for each successive technology node, and is in the millions of dollars for the most advanced nodes. The manufacturing cycle is also longer for the more advanced nodes.

The advanced nodes offer greater circuit density, with the density roughly doubling for each node. This reduces the manufacturing costs, but are the savings worth the extra NRE charges?

And there is the issue of circuit speed. A DDR4 interface needs at least 65 nm for implementation. A PCIe G3 needs 28 nm. And a mixed signal part can be successfully implemented at 180nm or less. The application sets a lower limit on the technology node.

So how do you determine the optimum node? First, let the speed set the lower limit. And trade off the manufacturing cost versus the NRE cost for your anticipated volume. As a rough rule of thumb, the manufacturing savings should pay for the increase in NRE charges within 6 months.

2013 is almost over, and we have had a good year.  At a minimum, our sales have doubled this year, and we have a good chance to triple sales for next year.

Double and triple digit growths are worthy, but they bring with them new challenges to address that we here at Tekmos enjoy taking on.  You can handle a little growth by working more efficiently and by just working a little harder. Tripling our growth means addressing the bigger picture.

Tekmos’ solution is to change the definition of some jobs, and to delegate into a new level of management. The process of identifying our growth opportunities means concentrating on our products, services, customers, channels and geographic areas that generate the largest proportion of revenue and profits.

An evaluation of the overall performance of Tekmos is ongoing and involves measuring and benchmarking profitability, rate of revenue growth and our reputation with our customers. This year we successfully entered new markets, created new products that appeal to that new customer base and as always, Tekmos provides an outstanding level of customer service. We will continue on that path for 2014.

We are going to make a cautious bet on growth.  We will grow, and be a leader in the semiconductor industry as we have already demonstrated with our high temperature ASICs and Microprocessors for extreme