This archive includes three IBIS models for EFR32FG23 and EFR32ZG23 devices.

efr32xg23_qfn40.ibs is for any device in the 40-pin QFN package (QFN40),
regardless of temperature grade, that has a "010" or "020" feature set
as explained in the Ordering Information section of the datasheet.

efr32xg23_qfn40_hfclkout.ibs applies to QFN40 devices that include a
high-quality HFCLKOUT pin and have the "011" or "021" feature set, again,
regardless of the temperature range.

Finally, efr32xg23_qfn48.ibs is for any EFR32FG23 or EFR32ZG23 device in
the 48-pin QFN package (QFN48), regardless of temperature grade.