What does m=10 mean in MOS schematics?

[chinito]

transistor layout

I've seen some schematics of MOS with m = 10 etc. What does it mean when you say multiplier (I assume that's what m stands for) is 10 for this transistor? Does it mean 10 parallel transistors of same size or what? Thanks in advance.

 

[bear7679]

Re: transistor layout

It means 10 parallel transistors of same size.

 

[DReynolds]

Re: transistor layout

Chinito, bear7679 is correct that M means 10 parallel transistors of the same size, but it does not answer the question of how are they drawn... one device with 10 stripes or 10 instances of a one stripe device. If you use a tool like virtuosoXL, it will treat M as multiplier, and place 10 individual devices down (by default) ... which is almost never what you want!! In your schematic, do you have a fingers or stripes variable as well as M or just Mso you can tell exactly what the layout should be?


David Reynolds

 

[Alles Gute]

Re: transistor layout

I agree with the above two replies. Multiplication means in parellel.
By doing this, you can reduce the gate resistor and reduce the R*C delay.

 

[aken_lu]

Re: transistor layout

i agree the upper isues.
In addition, this most happens in the input MOSs of differential OPAMP where need good matching.