Electronic Design

Standard Logic Is As Viable As Ever

The death of standard logic has been greatly exaggerated. Standard logic building blocks, including gates, flip-flops, and buffers, have existed for over 30 years. Many in the industry have called these parts obsolete for the last 10 years or so, particularly as ASIC and system-on-a-chip (SoC) technologies have gained prominence. In fact, this could not be further from the truth. Typically, every ASIC or SoC in a system requires a few associated standard logic devices. As mask costs balloon, the cost to re-spin an advanced design becomes prohibitive when minor changes are required. Adding a few standard logic devices saves time-to-market and mask-cost dollars.

Over 20 family types of standard logic are in production today. Most of these families are in the mature to declining stage of their life cycle. However, new applications continue to develop for standard logic. All portable devices, such as notebooks, handheld, wireless networking, and cellular phones, require the use of standard logic. Manufacturers of other IC product categories, like DRAM, flash, MPUs, and so forth, focus R&D efforts on migrating to smaller process geometries that require new billion-dollar fabs. Standard logic manufacturers don't follow this trend.

The focus is to reduce voltage and power consumption, combined with smaller packaging, to better fit in new, small portable devices. Thus, very low-voltage device families are in a growth mode. Single-gate-type devices are also on the rise. Companies like Fairchild have introduced logic gates in miniature packages: Fairchild trademarks its products as TinyLogic. Some other major participants in this market include Texas Instruments, Philips, and On Semiconductor.

Standard logic has suffered as well in this past downturn from excess inventory and weak demand. This situation is now behind us. The growth in unit demand experienced during 2002 is expected to continue through 2003 and 2004. Low-voltage parts and miniature packages will be the strongest participants in this expected surge.

Bus interface support represents another area of strong growth. With all of the new high-performance processors and network support chips, the number of buses and the need to support multiple memory interfaces will ratchet up the demand for off-chip support to drive heavily loaded buses. Single-ended bus transceivers have been the mainstay of the industry, but LVDS-based (low-voltage differential-signaling) bus interface circuits are gaining popularity due to their higher noise immunity.

In addition, there's a lot of momentum swinging in favor of serializer-deserializer circuits to replace wide parallel buses with a few high-speed serial channels. This is already happening in the networking arena with interface standards such as XAUI and SFI, which provide 10-Gbit/s aggregate data throughputs. In the embedded processor and PC sectors, we're also seeing interfaces like Hyper-transport, serial ATA, and PCI Express getting much attention as replacements for parallel interfaces to reduce pin counts and cabling costs.

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