IBW is dependent on the RFE mode used and they are 100MHz (ZIF mode), 40MHz (SH mode), 10MHz (SHN mode), 50MHz (DD mode), and 100kHz (HDR mode). It can also be set to other values using Decimation for ZIF, SH, SHN, and DD.
Refer to the Table 2 of R55x0 Programmer's Guide or R57x0 Programmer's Guide for more information.
The attached document shows all different operating bandwidths for R serial products.