Development of World’s Highest Power Efficiency Analog To Digital Converter by Fujitsu
In digital converters, the analog-to-digital (A/D) converters often responsible for a large share of the equipment’s total power consumption, making them an clear target for solution capable reducing power consumption. Currently, the pipelined A/D converters are mostly used in various digital devices and mobile phones. However, pipelined A/D converters include analog circuitry, which hampers the further miniaturization of the internal circuitry. Alternative to pipelined A/D converters are SAR (Successive-Approximation-Register) A/D converters, due to the fact that SAR A/D converters contrary to pipelined A/D converters do not require amplifiers plus they are compact in size and consumes less power.
Furthermore, SAR A/D converters require only simple internal analog circuit, not to forget their amenability to miniaturization processes. However, one shortcoming with SAR A/D converters is that they are not amenable to run at high speeds, due to the fact that they are susceptible to variations in electronic characteristics that exists in manufacturing. Due to this short coming SAR A/D converters have only been used at low speed ranges of 10 megasamples per second (MS/s) or less. In response to this technical challenge, Fujitsu Laboratories developed a SAR A/D converters with 10-bit resolution and a 50 megasamples per second conversion rate, attaining the lowest power consumption among any A/D converters in this class of 820 uW. this new development result in more efficient A/D converters which make possible the manufacturing of smaller and more power efficient system LSI as well as an effect on over all power efficiency of device itself. The development of a new SAR A/D converters were made possible through Fujitsu Laboratory’s development of a “digital assist” technology capable of internally detecting and automatically compensating for malfunctioning caused by variation in electronic characteristics as well as variation in temperature and supplied voltage. This will contribute to removal of design restriction that had previously limited elements above a certain size, in order to ensure a reliable degree of precision. SAR A/D converters built with this technology are able to cut power requirements by some 90%, with only 1/10th the surface area for the A/D converter itself. Fujitsu Laboratory will work toward application of this technology in digital home appliances, mobile phones, as well as 1seg and Full-Seg mobile phone digital TV broadcast tuners. as part of the future development,the company is also work on adopting the technology for further miniaturization processes.