In the world of circuit design, we often hear that analog doesn't scale. This, apparently, is hogwash.
"You can scale it [analog]. You just have to do some optimization," said Joseph Shor, a principal engineer at Intel Corp., in a presentation made that the International Solid State Circuits Conference in San Francisco Tuesday (Feb. 28).
Shor, who presented a paper about a thermal sensor included on Intel's newest microprocessors, said his group demonstrated the ability to scale the sensor by a factor of 3X from the 32-nm node to the 22-nm node. "It sort of busts the rumor at Intel that analog doesn't scale," Shor said.
Shor said that since his team presented data about the processor at an internal Intel conference last year, other groups at Intel have been scaling analog.
According to Ajith Amerasekera, a Texas Instruments Fellow, the power dissipated in analog circuits does not scale as readily as digital circuits for two main reasons. The first is that, at smaller dimensions, matching of analog circuits becomes more difficult. The second is that the lower voltages in the scaled technologies result in less voltage headroom and a lower signal-to-noise ratio, requiring greater effort to compensate for.
Amerasekera, who said TI has been successful in scaling down the power consumption of its analog chipsets, said analog scaling is accomplished through paying attention to power dissipation and innovative design techniques that eliminate circuits in a design that are unnecessary.
"It's a question of how hard do you want to work to get there," Amerasekera said. "A lot of people give up and say that you cannot scale analog circuits."
Amerasekera said digital circuits had the same issues that analog is dealing with in terms of power scaling, particularly around the 90-nm node. Chip makers overcame these hurdles with new design techniques for power management and advancements in EDA tools.
"It's the same concept for analog. It's just more complicated because there are so many more different types of unique circuits," Amerasekera said.
Gene Frantz, a TI Principal Fellow, said a lot of power scaling issues can be overcome through asking fundamental questions about design techniques and procedures. "It's always worthwhile to question the status quo, particularly in technology," Frantz said.