Cs_mosfet Amplifier Troubleshooting

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The discussion focuses on troubleshooting a CS MOSFET amplifier where the simulated gain of -11.3 differs significantly from the hardware gain of -40 to -45. The user is utilizing a BS170 MOSFET and has experimented with various capacitor combinations without success. Key suggestions include verifying the correct transistor and resistor usage, as well as confirming the DC operating point. Additionally, there are inquiries about measuring the transconductance (gm) and threshold voltage (Vgs(th)) to ensure accurate performance. Accurate measurements and component verification are essential for resolving the gain discrepancy.
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Hi all,

I am studying cs_mosfet amplifier and i have simulate one simple amplifier with VDD=+12v Vs=1v ID=0.5mA gm=1mA/v Vd=6v. I am getting a signal that is amplified by gain -11.3 by calculation and also on simulation but when doing on hardware i am getting gain around -40 to -45
I am using Bs 170 mosfet.

I have tried various combination of capacitors but still gain comes around -40...can anybody suggest me where is the mistake?
 
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can anybody tell me how to attach file here?
 
How can you be sure that your real MOSFET Bs170 will indeed have gm = 1m?
Do know how to measure Vgs(th) and how you can find K - factor ?

PS Go advanced ---> Attach Files
 
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Can you verify you are using the correct transistor?

Can you verify you are using the correct resistor?

Have you verified the DC operating point?
 

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