problem on constant gm

[mesfet]

Hi All,

I am trying to understand the constant-gm circuit more. Please refer to the enclosed screen capture. How come Iout is not constant with with VDS sweeps from 1 to 3V?


Thanks,
Mesfet+

 

[xwcwc1234]

May be you have a wrong bias point . Check the spice output for operation point analysis.

 

[hr_rezaee]

Hi
1- The current is independent of Vdd if we have a little change in it, no 200%.
2- check the bias points
regards

 

[nassim_el85]

hi

you will have constant current until your transistors are remain in saturation region (not for the hole range of VDD), you should find the range.

 

[mesfet]

Thanks all! After I change the resistor to 1K, the circuit works!

Mesfet+