Hi Jimmy,
for NFC devices there is no such spec for bandwidth and the transmitting power.
The "bandwidth" depends on the antenna design is defined in the related NFC / ISO Standards.
Similar for the transmitting power: the related measurements use the NFC / ISO Standards, which define power requirements for the tags (= minimum required field strength), and then define the related operating distances.
However, for comparison the transmitting power can be indirectly derived from driver supply voltage TVDD and the maximum allowed driver current ITVDD.
BR,
Renke
