UK Firm Introduces Multiple
System Level IC Alfred B Vollmer, Munich
Wolfson Microelectronics Ltd of Edinburgh, Scotland (UK), has introduced to the market a system level IC dubbed WM8044 which is intended for use in flatbed scanners, color photocopiers, digital cameras, color faxes and machine vision systems.
According to the managing director of Wolfson Microelectronics, David Milne, the chip will enable scanner manufacturers to bring color scanners into the price range of consumer electronics.
Wolfson Director Milne
"We can do all the signal processing in a chip that costs less than 20 dollars," said Milne. He added that the WM8044 is currently being designed in next generation scanner solutions by several Taiwanese companies. "The Asia Pacific region will be a key customer market for our new chip," Milne said.
The WM8044 is a monolithic CCD analog to digital interface subsystem compatible with 600 dpi CCD image sensors which can be configured for color or monochrome operation. An input multiplexer allows color operation with a single on-chip 12-bit AD converter. The device converts at a rate of six million pixels a second and uses DSP circuitry to correct for non-ideal CCD image sensor and scanning system characteristics.
Cost-effective grey scale operation is obtained using a single multiplexer input. WM8044's three channel input multiplexer and sampling function has two basic modes of operation: normal sampling and correlated double sampling.
Digital DC Restoration Provided
The internal sample and hold allows all three channels to be sampled simultaneously in color operation. Three DACs, each of them 8 bit plus sign, are provided in order to allow bipolar adjustment of the DC level of the signal at the ADC input. Digital DC restoration is provided following the AD conversion.
Variations in offset and luminance across a scan are dynamically corrected on a pixel by pixel basis, using calibration data provided by an external data store. Provision is made for global adjustment of gain, for contrast and color balance and offset for brightness. The output word-length can be programmed to be 8, 10, 12 or 16 bits, and a programmable threshold detector is provided for use during calibration and in OCR applications.
Wolfson's 8044 CFN
The device's architecture was developed by Wolfson in conjunction with Texas Instruments of Dallas, Texas (USA), utilising TI's pipeline A to D architecture. Texas Instruments also manufactures the chip. There are parallel interfaces for dynamic adjustment input and tri-state output data.
A three-wire serial interface is used in order to configure the device and to program internal registers. The device works with a single 5 V supply and is available in a 68-lead PLCC package. A complete development kit with evaluation board, ISA PC adapter board, cables, user's guide and software for PCs (including driver utilities and source code) is also available.
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