Current mirror sizing limited trans. length

Hi.
I have current reference for current mirror for example : 2 pmoses connected in serial (effective L x2) and resistor. 
The pmos transistors are with min W/M/NF and max L.

 Upper pmos has : Vth -360mV, Vds 42mV, linear region.

The 2nd pmos : Vth -354mV, Vds 377mV , saturation region.

As far as I get it , important that the 2nd device is in saturation.

I want to get lower current from this reference (1/2 , divided by 2) , and I can't to reduce W/M/NF (it is already min) I want to change the reference:
set M (multiply) to 2 and in order to keep the same W/L , I need to increase L (already on max), and I set 4 pmos transistors in serial.
I get the necessary current as before  , and 3 upper transistors in linear region , but the 4th is in subthreshold (Vgs < Vth). Vth -354mV, Vgs=Vds 345mV.

How to figure it out? Please advice.