Design a Cascode amplifier using suitable topology to meet the specifications( by Varying W/L ratio) . VDD is 3.3V
You cannot see your 3dB point because the bandwidth of your amplifier is much larger than what you're sweeping in frequency.
Also, your biasing is improper. M6 and M4 are just cascode devices and are there to provide a boost in the r_out. M8 however is a current source, just like M5 and M3. Therefore, the gate of M8 should be connected the diode generated by M5 as that is the actual current source. I would suggest that you use a wide swing cascode biasing instead.
The mirroring of M5 and M3 are far from optimal and you're not getting a proper current mirror based on W/L ratios. You're introducing a lot of error by biasing it that way. EDIT: At the moment, for biasing use ideal voltage/current sources and as many as you want until you get the results you want. After you meet your specs work on the bias separately as that won't affect your result at all provided it's a proper biasing scheme. In other words decompose the problem like below

Finally, for a gain of 45 dB (depending on the process technology you're using) I would say you can drop the cascode on M4 and play with the L's of M8 and M9. I could draw it for you but I'm assuming this is a homework/project problem for school :)
Be sure to understand all the trade-offs here. These will come in handy on job interviews as interviewers ask exactly how to fix circuits like these.