Over recent years, the definition of what constitutes a precision DAC (digital-to-analog converter) has changed rapidly as semiconductor processing and on-chip calibration technologies have advanced. Not long ago, 12-bit DACs were considered to be precision devices; now widely available 16-bit accurate digital-to-analog converters are commonly used in precision medical, instrumentation, and test and measurement applications.
But even 16 bits is no longer state of the art, as 18 and even 20-bit units are available, This article looks at issues involved in using a 1-ppm (20 bit) DAC. It is presented in pdf form (no registration required) as follows:
Part 1 of this article looks at a 1-ppm DAC and associated support circuitry, error sources, and performance measures. To read it, click here.
Part 2 discusses 1-ppm circuit complexities including noise, temperature drift, thermoelectric voltages, physical stress, long-term stability, circuit construction and layout, and voltage references. It will be posted online on March 25.
About the author Maurice Egan is a senior applications engineer for the precision converter group at Analog Devices, Inc. He holds a bachelor's degree in electronic engineering from the University of Limerick, Ireland. He can be reached via email at email@example.com.
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