Hi there,
What is the minimal L for the MOSFET? It is a good practice to use about 10x Lmin in given technology to minimize channel length modulation, improve the threshold voltage stability (VTH vs L) and minmize the dependency on process variations (MC simulations).
The transistors in current mirror should have the same W/L and number of fingers (if mirroring ratio is 1:1), same VDS above VDS_sat and the inversion (VGS-VTH) as high as possible to mirror the current properly.
Judging by the voltages and currents, you are using rather older CMOS technology and L = 1um might not be enough.... plus your VDS conditions might not be ideal for correct mirroring either, but that is not shown in your picture.
Bruteforce method can be used here, I think... Just set W and L of both transistors as variables. W_M91 = W_M92 = W and the same for length. L_M91 = L_M92 = L = 10x Lmin and step W through the DC / OP analysis. This way you might tune the W/L to your liking....
Shlooky
Hi
shlooky,
Thank you for your reply,
What is the minimal L for the MOSFET?
I am working on 0.18um technology.
It is a good practice to use about 10x Lmin,
I tried to maximize the L but I have to maximize the W also, and I don't want to be the transistor too big. and I am already using 1um for L.
The transistors in the current mirror should have the same W/L and number of fingers (if mirroring ratio is 1:1), same VDS above VDS_sat and the inversion (VGS-VTH) as high as possible to mirror the current properly.
I am training to do this but I can not. why? I don't know how!!
Judging by the voltages and currents, you are using rather older CMOS technology and L = 1um might not be enough,
I don't understand your view point on older CMOS technology.
plus your VDS conditions might not be ideal for correct mirroring either, but that is not shown in your picture.
See the attached new picture please,
Bruteforce method can be used here, I think... Just set W and L of both transistors as variables. W_M91 = W_M92 = W and the same for length. L_M91 = L_M92 = L = 10x Lmin and step W through the DC / OP analysis. This way you might tune the W/L to your liking....
I am a beginner in using Cadence, and honestly, I dont know how? I am changing manually.
I hope to get answer.
regards.