ADC fronts up CMOS image sensors

The WM8200 is a high-speed A/D convertor that delivers a full 10bit resolution at 40Msample/s.

The WM8200 is a high-speed A/D convertor that delivers a full 10bit resolution at 40Msample/s.

Developed by Wolfson Microelectronics, the low-power convertor has a 3bit PGA, adjustable internal voltage references, built-in clamp with a 10bit DAC, and a power down mode.

Performance data include: typical integral nonlinearity +/-1bit, typical differential nonlinearity of +/-0.3bit, an effective number of bits of 9.5, and an active power consumption of 100mW from a 3V supply, declining to less than 0.1mW in power-down mode.

Such statistics mean that the WM8200 is ideally configured for use as an analogue front end (AFE) for digital still cameras using CMOS sensors.

Wolfson has long experience in providing AFEs to use with CCD sensors in products such as flatbed scanners, however there is a growing need for AFEs for use with CMOS sensors.

Leading analysts including Frost and Sullivan predict that CMOS sensor sales will exceed CCD sales by revenue in 2004.

VP of Marketing Julian Hayes reckons that Wolfson's experience in high-volume supply into imaging markets is an excellent basis from which to ensure competitiveness with this product, using Wolfson's sales teams in the US, Taiwan, and Japan.

"We designed the ADC because our target customer base has many different application styles.

We believe that this ADC will be at the heart of a new standard of digital still camera, offering what used to be considered professional or high-end consumer performance at price points within the reach of the average amateur photographer.

Good ADC conversion performance is far easier to achieve with conversion on separate silicon and this product will help make quality camera design easier for our customers".

The WM8200 is currently available in a lead-free 28-lead chip-scale package, with a 5 x 5 x 0.9mm footprint.

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