Beating time

Electronics circuits are nothing without their heartbeats – the vital timing source akin to a metronome that allows the constituent parts to act in unison. But electronic circuits are generally getting larger – meaning clocks have to be distributed over longer distances – and are required to operate at higher speeds. Not only that, parameters such as skew and jitter become more problematic. And if that wasn’t enough, some devices are running from different supply voltages. Providing an overview of the problem, the preamble to the clocking session at this year’s International Solid State Circuits Conference in San Francisco, made this observation. ‘The relentless pursuit of performance continues to drive clock frequency requirements into the multi GHz range. This greatly challenges designers, as the need for speed is in direct conflict with the need to keep power and thermal dissipation within system bounds. In response, designers are inventing increasingly innovative techniques for delivery of high performance clocks at low power levels. As process technologies shrink and voltages scale, full digital solutions to ‘super speed’ clock generation which are tolerant to process variations are gaining ground over analogue techniques’.