Other Parts Discussed in Thread: , TIDA-01570
I'm creating my own board around the AWR1642, and basing it on the TIDA-01570 design. I noticed some differences in the power supplies between TIDA-01570 and AWR1642Boost. I would appreciate some guidance in selecting my power supply components.
1. The automotive board uses only one LDO, which is for the 1.0 V RF power supply. The AWR1642Boost uses a 1.3 V supply and runs the internal LDO on the AWR chip. I understand that bypassing the internal LDO reduces heat dissipation by the AWR chip, but is there a downside to this approach? Is noise performance better if the internal LDO is used?
2. Another difference I see is that the automotive board has ferrite beads between every power supply and the AWR chip, while the AWR1642Boost has none. According to this document, LC filters like the automotive board uses are more power efficient than LDOs, but noisier, and that noise can get into the RF signal. However, it seems that some of these ferrite beads are unnecessary. In particular, the FB after the 1.0V LDO and the FBs for 3.3V and 1.24V (digital) supplies. Can I remove those without hurting the noise performance?
3. It also seems that adding an LDO for the 1.8V supply on the automotive board would benefit the noise performance, since swra557 indicates that the 1.8V and 1.0V power rails are both sensitive to input supply ripple. Is this correct?