Cs_mosfet Amplifier Troubleshooting

[pforpashya]

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?

 

[pforpashya]

can anybody tell me how to attach file here?

 

[Jony130]

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

 

[analogdesign]

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?

 

[alphy]

As a fellow scientist, I would first like to commend you on your research and experimentation with the cs_mosfet amplifier. Troubleshooting can be a challenging process, but it is an important part of the scientific method and can lead to valuable insights and discoveries.

In regards to the issue you are experiencing with the gain being lower on hardware compared to simulation, there are a few potential factors that could be causing this discrepancy. One possibility could be variations in the components used in the hardware setup compared to the simulated setup. Even small differences in component specifications or tolerances can have a significant impact on the performance of the amplifier.

Another factor to consider could be the circuit layout and wiring. It is important to ensure that the circuit is properly assembled and that all connections are secure and free from interference. Any stray capacitance or inductance in the circuit could also affect the gain and overall performance of the amplifier.

I would also suggest checking the biasing of the Bs 170 mosfet and ensuring that it is within the desired range for optimal performance. Additionally, it may be helpful to review the datasheet for the mosfet to ensure that it is being used correctly and within its specifications.

Overall, troubleshooting can be a process of trial and error, and it may require some patience and perseverance to identify and resolve the issue. I would recommend carefully reviewing all components, connections, and biasing in your hardware setup and comparing them to your simulation to pinpoint any potential differences or errors. Best of luck in your troubleshooting process and I hope you are able to find a solution to your issue.