I'm designing a 3 stage amplifier, being the first stage a common source MOSFET amplifier (using a 2N7000 MOSFET). I have made some basic calculations to calculate the resistor values. It must have a 1.25M Ohm input resistance, and a maximum drain current of 10 mA
I have calculated some values and simulated the common source amplifier. The gain seems to be fine but the output waveform seems more like a square wave rather than a sine wave.
Does anyone have an idea on what might be happening? How can I solve this?
I used the characteristics of the MOSFET that I obtained through a DCA Pro:
V(GS(on))=2.390 V at i_D=5 mA at i_G=5 μA
V(GS(off))=1.678 V at i_D=4.7 μA
gm=27.7 mAV at i_D=3 mA to 5 mA