Electronic Design

After The System-On-A-Chip Revolution, Where Will Pc Boards Stand?

Have you heard the latest news? Silicon designers are shrinking pc-board interconnects and putting them all on a single chip, eliminating the need for the board. The connections between all of the chips, normally done by the pc board, can now be done between separate functional blocks all integrated on a single chip.

These new system-on-a-chip (SoC) designs will eliminate the need for circuit boards. When the whole system is a single chip, all you need is a few wires for the I/O interface. Next-generation products won't need any circuit boards in them. The SoC is the pc-board killer—right?

Wrong! This is just the hype intellectual-property (IP) marketeers are pushing to further position the SoC revolution as the true future of microelectronics. The reality is that an SoC is just another type of chip design. It's in the same class as field-programmable gate arrays, ASICs, and full custom design ICs. If the marketing hype holds true, then SoCs will reduce the design time for complex and large chips by allowing the reuse of building blocks such as digital signal processing, processor, bus-interface, memory, and graphics cores.

Did 10-million-gate ASICs eliminate the need for pc boards? The answer can be simply responded to with an emphatic "No!" In fact, their introduction required the use of even higher-value substrates due to the higher bandwidth of signals, increased number of I/Os, and lower impedance requirement for the power and ground distribution to these ASICs.

These and other signal-integrity topics will be covered in great detail at the upcoming Pc-Board Design Conference West. The show will be held this month at the Santa Clara Convention Center located in California.

There is currently a lot of uncertainty regarding the future of SoC designs. For example, will, the non-recurring expenses (NREs) for designs really be over $1 million each? Will it really be cost-effective to integrate expensive processor cores with inexpensive memory or analog functions? Who will take responsibility for all of the different cores working together correctly? And, who will debug a malfunctioning design? The manner in which these issues are resolved will ultimately determine how much of a niche SoC can take over.

In the meantime, however foggy the future role for SoC might be, the role of the pc board remains crystal clear. Within each form factor of product size, the importance of the pc board will increase, not decrease. Whatever the function integrated on the chips, it is a given that they will have wider-bandwidth interfaces, more I/O leads, and lower rail voltages.

As a result, the same signal-integrity problems pc-board designers are ripping their hair out over today will only get worse in the future. Ultimately, those companies with expertise in minimizing signal-integrity problems in their boards will be the companies to prosper with the next-generation silicon, regardless of whether they use 20-million-gate ASICs or 20-million-gate system-on-a-chip designs.

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