high-swing current source
The left one is part of a high-swing cascode mirror.
The right one is a cascoded mirror, but lacking the bias generation circuit for the cascode transistor. So, both circuits aren't complete.
In the left circuit NB2A programs the current, and NB2B is a cascode device that improves matching. The gate voltage of NB2A is the mirror programming current, and the gate voltage of NB2B must be connected to some circuit that generates a vbias for it.
NB1 is the circuit that generates this bais voltage for the cascode.
Assuming that the mirror transistors are identical, just make the L of NB1 between 1/4 and 1/5 of the L of NB2 and you will generate a vbias that keeps drain voltage of NB2A just above the saturation limit.
This circuit is described in the book by Johns and Martin, btw. Solve the square-law equation for NB1 in terms of the size W/L of NB2 and the vdsat of NB2 and you'll get this result.