Other Parts Discussed in Thread: ADS5296A
Hello All,
I have employed two ADCs in my design like those in TIDA-01022 and I have questions regarding AGND and DGND in the layout. I greatly appreciate if you would help me with questions related to TIDA-01022
As Fig.1 shows, In this design, All fully differential amplifiers (FDA) are placed over AGND and the ADCS and the Clock are placed over DGND. As Fig. 1 shows one continuous ground is incorporated for the ADC which belongs to the DGND. However, the inputs to the ADC sees AGND where the FDA are placed. Here I have some questions
1- AGND and DGND are connected close to the inputs of ADC using ferrite bead (FB), however, they are not placed and are DNP. Does it mean that there is no need to connectAGND and DGND. In other word if one uses this approach to separated DGND and AGND is using ferrrite beads mandatory?
2- Why the GND for the ADC was not designed such that it belongs to AGND rather than DGND? (see Fig.2)
3-Why AGNF and DGND are not connected under ADC like the one shown in Fig.3. (In the evaluation board given for ADS5296A this layout is suggested) (layout like Fig.4 as another example)