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Unity gain Frequency(ft) and Max oscillator frequency(Fmax) simulation of a MOSFET.

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srikanthmk

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Unity gain Frequency(ft) and Max oscillator frequency(Fmax) simulation of a MOSFET in HSPICE.
I biased the circuit in saturation region and applied input current with a frequency sweep. But the current gain seems to decrease instead of increasing.

My netlist is a follows:
*Tranisitor
M1 OUT IN 0 0 CMOSN L=0.12u W=1.5u
L IN DCinp 10

*setup sources at drain and gate
Vcc OUT 0 DC 1
Vin DCinp 0 DC 1
Iin IN 0 AC 1

* AC Sweep
.OP
.AC DEC 5 10Meg 100G
.PLOT I(Vin) I(Vcc)
.OPTION POST
.LIB "/home/doust/srikanth/ibmModel/ibm_013um_model.txt" CMOS_MODELS
 

What do you mean? It must decrease, not increase, and you are looking for the value it becomes unity.
 

Sorry I misquoted my question, The current gain was increasing instead of decreasing ( which is not intuitive).
True, as mentioned by you the I need extract frequency when current again is 1.
Could please give feedback on my netlist?
 

srikanthmk said:
Unity gain Frequency(ft) and Max oscillator frequency(Fmax) simulation of a MOSFET in HSPICE.
I biased the circuit in saturation region and applied input current with a frequency sweep. But the current gain seems to decrease instead of increasing.

The terms "oscillator frequency", "input current" as well as "current gain" sound a bit confusing while speaking about a MOSFET.
(What is the oscillator frequency of a MOSFET?).
Why do you use an inductor L as input element?
Click to expand...
 

are you sure that's the way to simulate fT?
 

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