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Variable Gain Amplifier

Yared Yemane SEyum

Feb 28, 2017
2
Joined
Feb 28, 2017
Messages
2
I would be glad if someone could help with the design and simulation of variable gain amplifier using ORCAD Pspice. The VGA is built from MOSFETS.
 

Yared Yemane SEyum

Feb 28, 2017
2
Joined
Feb 28, 2017
Messages
2
The concept is that we have to replace the drain resistors by MOSFETs so that we can control the gain by varying the small signal trans-conductance gm since Av=gm*Rd. But my questions is how to vary the value of gm. I tried to give the inputs a differential mode sine source but the simulation showed an error. And when I also changed the input to a DC source, still the same error "unable to find nomd.lib". I have attached the schematic and simulation result as pdf.
 

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  • PSPICE Simulation.oxps.pdf
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