How to design portable handsets using CPLDs

By Michael Gordon, Xilinx
May 21, 2008 -- pldesignline.com

This tutorial describes the different ways in which CPLDs can be used to address the shortcomings associated with handset platforms.

Portable consumer electronic designs such as cell phone handsets, PDAs, and MP3 players are typically very high-volume products. Because of this, product designers first look to ASIC or ASSP methodologies to pack the greatest functionality into tiny, portable packages. But CPLDs are rapidly becoming a more attractive proposition in this market as they meet the density and power requirements of many portable applications while adding the ever more important benefit of helping customers quickly create designs that seize market opportunities. They also help designers overcome many of the shortcomings of popular handheld platforms such as OMAP-, XScale- or i.MX.

The emerging need for flexibility

Using an ASIC or ASSP will typically meet a design project's specifications for functionality and power consumption. However, there are other factors design groups targeting the consumer market must take into account. And a chief emerging factor is flexibility. Indeed the consumer world is rapidly changing and features your team envisioned at one point in time can become obsolete within a matter of months, as you and your competitors react to ever-changing technologies and market dynamics to deliver differentiated solutions.

As the consumer electronics business becomes much more competitive, design teams need to make design choices that will allow them to produce the right products at the right time to ultimately help their companies sustain and hopefully build market share. But this need to be agile in the market and makes picking the correct ASSP or designing the right ASIC a very difficult task.

Today's designers are now looking beyond the fixed architecture of ASICs and ASSPs to discover the innate design flexibility and time-to-market benefits of programmable logic. Today's low power CPLDs offer portable device designers a viable alternative to standard cell technology and provide some of the lowest cost, lowest power solutions.

Various CPLD families are now priced low enough that they are comparable in price to discrete logic devices but give design groups the added benefit of modifying their designs quickly to seize market opportunities.

Let's examine ways to expand beyond the limitations of today's ASIC/ASSP portable handset solutions, with simple, cost-effective, low-power programmable logic using CPLDs. As most handsets today are OMAP-, XScale- or i.MX-based designs, we'll describe how CPLDs can offer solutions to several problems that commonly pop up with these portable mobile platforms.

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