Changing times

Currently, almost all electronic devices use a vibrating quartz crystal to provide a timing reference. The material has a long-established reputation for accurately converting mechanical vibrations to electrical signals and is used in a wide range of electronic devices from mobile phones to radio transmitters.

While quartz crystal has an unwavering ability to provide a stable timing reference, changes to electronic products over recent years have highlighted its limitations. For instance, a crystal oscillator can be up to 6mm thick, taking up crucial space in increasingly miniature electronic devices. It also lacks the ability to integrate into silicon, which can further increase manufacturing costs.

‘Quartz is basically an 80-year-old technology and is the last simple commodity component left that’s not silicon,’ said Ian Macbeth, chief executive of eoSemi. ‘But there is a shake-up happening now, driven by media phones and modern handsets, where space is at a premium.’

The company claims to have developed a silicon timing device with a square width of less than 1mm for low-frequency sleep-mode applications. The chip is expected to replace quartz crystals while working within the device’s silicon structure to reduce component size.

‘The main reason people haven’t done this before is that crystal is so good at doing its job and the need to shrink hasn’t been there until now,’ said Macbeth. ‘There are some technical difficulties too. Silicon oscillators just don’t behave when you heat them up so we’ve had to find a solution where we are able to exert extreme fine control over the output frequency and ensure it stays within tolerance.’

A precise linear fine tuning technique has been developed by eoSemi that is currently under patent application. Macbeth added that the method could be applied to a wide variety of silicon-based oscillator circuits to replicate the different frequencies produced by quartz crystals in temperatures ranging from of -40˚C to 85˚C.

The technology has attracted interest from several partners and received funding from venture capital firm, EV. The company plans to use the investment to bring a timing device to market by the end of 2011.