# How to obtain the basic parameters of P/N mos for manual calculation?

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#### aaronwu

##### Newbie level 5
Hi,

now I have P/N mos model(BSIM49), as we know, we need manual calculation to solve 80% op design issue, but how to obtain the basic parameters of P/N mos for manual calculation? such as K',Vt,lamda .etc. Thanks a lot!

#### leo_o2

op design question

You can find vth in the model. It is vth0.
You can also find tox,u to calculate K. Maybe you can find lamda by simulatingI/V curve.

#### DZC

##### Full Member level 3
op design question

It seems just a problem of figuring out the process parameters from the foundry's PDKs.

It seems just a problem of figuring out the process parameters from the foundry's PDKs.
You can look up the Parameters according to some textbook

#### aaronwu

##### Newbie level 5
op design question

Thanks leo_o2 and DZC! I only have model file, no textbooks. My concern is that if I find vth0, tox,u from the model, are these parameters enough accurate for manual calculation results?

I want to know original designer how to figure out these parameters or how to solve this problem. Thanks a lot!

##### Full Member level 4
op design question

aaronwu,

Here are some tricks to findout the Vth of device

1. Connect your NMOS device in diode connected fashion
2. Select W=10um and L= Lmin for your technology / 0.5um
3. Now apply Vdd = VDD given in your technology
across the Drain and Source so that Vgs=Vds
4. Now run .Op analysis
5. Check spice log file .. in case of hspice list file ..
you will get all its parameters ..

For Tox .. check the model card it is given ther ..

and if you are using MOSIS models generally all
these parameters are given for e.g.

TRANSISTOR PARAMETERS W/L N-CHANNEL P-CHANNEL UNITS

MINIMUM 0.27/0.18
Vth 0.50 -0.54 volts

SHORT 20.0/0.18
Idss 572 -277 uA/um
Vth 0.51 -0.51 volts
Vpt 4.7 -5.5 volts

WIDE 20.0/0.18
Ids0 19.9 -10.0 pA/um

LARGE 50/50
Vth 0.42 -0.41 volts
Vjbkd 3.1 -4.1 volts
Ijlk <50.0 <50.0 pA

K' (Uo*Cox/2) 169.1 -36.0 uA/V^2

source : https://lgjohn.okstate.edu/5263/processparam/t4bk_lo_epi-params.html

The procedure to find lambda is given in Holburg's book ..

Regards

#### aaronwu

##### Newbie level 5
op design question