PCI-DSS and IPS

["raimarm () gmail com" <raimarm () googlemail com>]

Hi All,
I am a technical orientated guy and not sure about my following question.
Is a IPS system in regards to PCI-DSS obligatory ?
If yes, would it be possible to take a FW with IPS functionality
rather to buy a dedicated IPS (like deep-inspection, smart-defense and
the like).
Many Thanks
rm