Cirrus Logic AN263 - Manual (Page 9)

AN263
AN263REV1 9
Figure 7 displays a similar series of plots where the filter/ buffer circuit has been redesigned to scale the
resistors to 10% of the previous values. Notice the improvements in the deviation from the ideal. With
these impedance changes, the deviation from the ideal remains minimal up to approximately 110 dB.
4. Conclusion
It is a relatively straightforward process to calculate and predict the system dynamic range for any com-
bination of analog-to-digital and digital-to-analog converter, as well as the maximum allowable analog
buffer and filter noise to achieve these targets. The difficulty is designing low noise analog buffers and
filters that meet the requirements of today’s leading edge converters. The combination of high-dynamic
range and the limited full-scale signal amplitudes typical of today’s converters create a challenging envi-
roment for the systems designer. The first steps are to recognize and understand the challenge.