Fluke JW EDN p1 free download

File name JW_EDN_p1.pdf

designfeature By Jim Williams, Linear Technology Corp FOR THE PRICE OF A SAN FRANCISCO DINNER, YOU CAN PUT STANDARDS- LAB PERFORMANCE ON A CIRCUIT BOARD. PART 1 OF THIS THREE-PART ARTICLE CHRONICLES A 1-PPM DAC AND ITS VARIOUS DESIGN OPTIONS, PART 2 IN THE NEXT ISSUE PRESENTS VERIFICATION TECHNIQUES, AND PART 3 DISCUSSES THE HANDLING OF PARASITIC EFFECTS. 20-bit DAC demonstrates the art of digitizing 1 ppm Part 1: exploring design options f you design and use precision instruments, a of DACs are still in use. (Part 2 discusses this type I 1-ppm measurement is a nearly impossible of DAC in more detail.) dream. This level of performance used to be at- Thus, a practical, 20-bit (1-ppm) DAC that is easy tainable only from large, slow, and expensive in- to construct and does not require frequent calibra- struments that require extreme care in handling and tion is a useful development. The scheme in Figure use. However, now a DAC design that uses a simple, 1 is based on the performance of a true 1-ppm ADC powerful feedback loop can capture the magic 1- with scale and zero drifts less than 0.02 ppm/