i am doubtful whether simple two stage class-A opamp can provide 160MHz UGB.please clear me if i am wrong.i thing we have to choose the folded cascode opamp for 160MHz ugb.
I think it may be the single stage fold-cascode amplifer with the gain-boost technique.
For the .25 mico technology, the bandwidth of two stage amplifier may be attained if offset is not dominant parameter with all minimum length design.
Use an OTA or so-called 2-stage CMOS Op-amp. The internal feedback is the key to push the linear bandwidth to 160 MHz, by means of gain boost in the gain stage.