Can anybody give me some advice on the low power high-GBW high output swing amlpifier?

[arron_tan]

We are required to design a fully-differential op-amp. The specs are listed below, and the process we used is TSMC 0.18um CMOS

Given the high output swing and high gain, our preliminary idea is folded-cascode+gain boosted, and the topology is shown below:

The GBW can be approximated by gm1/CL. With GWB>600M and CL~1pF, the gm1 should be larger than 3.77mS. However, according to the simulation, to achieve gm1 = 3.8mS, the ids1 is required to be around 450uA with a overdrive voltage of 150mV, which means the power can hardly meet the spec, i.e. less than 2mW.

Can anybody give me some advice? What type of amplifier topology should I use?

 

[dick_freebird]

Perhaps your problem is Rout and not gm. Or, improving Rout
costs less (current) than improving gm. Raising DC gain will move
UGBW. Since you mention nothing about optimizing L per device
position, this is my suggestion before jumping topologies.