How to design a voltage follower/Unity gain buffer circuit using MOSFET?
You can use an op-amp to provide feedback control to mostly eliminate the load dependence:



simulate this circuit &ndash; Schematic created using CircuitLab
In comments you said the reason you have not considered using an op-amp is &quot;I have area and power constraints&quot;. But your proposed solution is to use a second MOSFET.
Very likely you can find an op-amp that uses just as little area and less power than any solution that involves adding a second MOSFET.
For example, Mouser lists 215 op-amps in SC70-5 package (2.0 x 1.25 mm), with typical supply current as low as 350 nA (and almost all below 1 mA). Other options are available in packages (mostly &quot;wafer-level&quot; and &quot;chip-scale&quot; types) smaller than 1 x 1 mm.
The best choice of op-amp will depend on the required bandwidth and Vdd voltage, which you haven't shared.