What is the meaning of finger and multiplier in a MOSFET as we can see in the properties of a MOSFET?
I would highly appreciated if there are some diagrams and layout to be shown.
I have no idea what the multiplier does, in fact if have never used this at all in 16 years.
The finger parameter on the other hand is very helpful if you want to draw big transistors.
Changing the finger parameter simply creates parallel transistor gates to exactly the amount you
have entered. Image you have a device in the schematic 400u wide but you don't have 400u
of space in either direction but you have a nice little rectangular spot left. You create a single
transistor 20u wide and change the finger parameter to 20. This yields in a 400u transistor
with 20 "fingers" a 20u, drain/source areas already merged. You just have to do the wiring.
Simply try it !
In reply to baenisch:
This depends in the implementation of these parametersIn most cases I have seen- number of fingers is a pysical paramter which lets you fold your mos width a long with to several mos with width/finger and shared S/D areas.- the m is a multiplication factor for the simulator which multiplies the current though the devices.Bernd
In reply to berndf:
The m is the multiplication factor.
In Layout XL, for transistors, the m from the schematic is used to create multiple layout instances with common parameters.
i.e. for eg., a schematic instance M0 with total_width=6u, length=1u, fingers=3 finger_width=2u m=5
will result in 5 layout instances:
M0.0: total_width=6u, length=1u, fingers=3 finger_width=2u
M0.1: total_width=6u, length=1u, fingers=3 finger_width=2u
M0.2: total_width=6u, length=1u, fingers=3 finger_width=2u
M0.3: total_width=6u, length=1u, fingers=3 finger_width=2u
M0.4: total_width=6u, length=1u, fingers=3 finger_width=2u
Multiplier - number of Parallel MOS devicesFinger Width - width of each gate finger/stripe
Fingers - number of poly gate fingers/stripes used in layout