arron_tan
Newbie
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?
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?