how to find gain in cascode differential amplifier?

[shobha89]

Hai, i am shobha.i am doing my project "Design Cascode differential amplifier".i need schematic diagram of cascode differential amplifier with length and width.presently i am using 0.18u technology in virtuoso.but whatever length and width which i gave ,was not getting output.i want to find gain.
the gain vs frequency curve should be as low-pass filter curve.pls can anybody help me.using hspice how can i find it...........

 

[stuck_adc]

you need to fix the operating point first i.e. when you apply vdd/2 to both inputs you should get vdd/2 as output.
when you will achieve this your circuit will give you the maximum possible gain, while doing ac analysis don't forget to put the load capacitance at critical nodes.

to fix oupput to vdd/2 you need to modify w and l of some transistors of your design, these transistors depend on the architecture you are using.

hope this will solve your problem.

 

[shobha89]

thanks a lot.i didnt connected any capacitance while doing ac analysis.is ac analysis means ac response.what are the main things to be find in this project.pls anyone provide pdf's related or according to this topic.pls send to my mail
shobharani3@gmail.com.