Project Analog - February 2008 - (Page 14) Smart ADC Architecture How to increase ADC converter speed and resolution while reducing pin count By Ted Harris National Semiconductor / Santa Clara, CA www.national.com Contents Viewpoint Digital potentiometer application circuits Smart ADC architecture Layout techniques for high accuracy and resolution ADCs Analog news I n today’s world of electronic design, analog-to-digital converters (ADCs) play a pivotal role in translating real-world signals to digital representations. These digital signals are processed and manipulated to perform a variety of operations within a typical system. For high-speed ADCs, two innovation trends have pushed the technology along over the past few years. First, higher conversion rates are always needed. A wider signal bandwidth can be captured if the ADC samples and converts signals faster. Second, there is the drive toward increasing converter resolution. Increasing the number of bits within a converter improves characteristics such as signal-to-noise ratio and dynamic range. These two goals have worked 14 · ProjeCT ANALog · feb 08 together to drive the data bandwidth to ever-increasing levels. reduced fOrm factOr A continuing industry focus toward smaller physical layouts, has also, among other things, caused industry pressure to reduce component package size. In a monolithic IC, such as an ADC, this almost always means reducing pin count. At first glance, it would appear that the first two goals increased converter speed and increased converter resolution would lead to a direct conflict with the third goal of reduced form factor, specifically reduced pin count. Fortunately, there is a solution that can accommodate all three goals: by returning to serial data interfaces. Serial data interfaceS Serial data interfaces are nothing new. RS-232 has been an industry standard for decades. In the back of the mind of every board-level designer, however, is the latent assumption that parallel data structures will always be faster than serial data structures. While for those applications with the flexibility to employ some additional functional blocks, the rewards may be great. Microchip analog page Mixed-signal overview Sample center microchipDIRECT Reference designs/ app notes Technical training http://www.national.com http://www.microchip.com http://www.microchip.com/analog http://www.microchip.com/analog http://www.microchip.com/mixedsignal http://sample.microchip.com/Default.aspx?testCookies=true http://www.microchipdirect.com/catalogselection.aspx?returnURL=default.aspx http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1469&filter1=function&redirects=appnotes http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1469&filter1=function&redirects=appnotes http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1423
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