HI guys,

I was simulating a very basic NMOS transistor using spectre analog environment in order to obtain the Ids/Vgs plot. I used parametric analysis on Vds and dc analysis on Vgs to obtain the plot at 300K. Everything seems fine.

However, when i tried to switch the temperature to 4K ( as i need those simulations to run at 4K ), there were errors. The error messages were:

Error found by spectre during initial setup.
     M0.my_nch: The junction reverse saturation current is too small = 4.15 C.

Warning from spectre during initial setup.
     M0: 'Dvt0' = -15.0839mV is negative.

What do the messages mean?

Please help, urgent.

Kindest regards,

Sphere

Thanks Yawei for your prompt reply!

It is going to be used to amplify signals from single electron transistors operating at 100mK to 4K. However, the major concern here is the thermal noise and flicker noise. The Id characteristic curve is similar at 4K and at 300K( not same, but similar i think ) and thus can be used.

Is there a way I can set the spectre analog environment to simulate those transistors at 300K but make it think that it has a noise temperature of 4K or less? I'm a real noob in Cadence spectre but i'm willing to learn hard!  ;D Kind people out there please point me to the rite direction!

Cheers

Sphere

Thx Ken WIll try it out !