why my LNA gain is negative(db)?

Hi

Is the DC source connected to LNA?

Regards

hi,
yes,it has connected to DC source

OK

Upload Your Schematic.

There are many things to LNA has negative S21.

Regards

Hi ssdd,

A negative gain for LNA suggest many things. First, your device may be blowned. This will cause your transistor to act more like a resistor at the gate-source region. I'm not sure which device you are using but, check the manufacturer datasheet to make sure that you're applying the proper temperature on the various pad when soldering your device (if you've done this yourself). Another thing you should check is to see whether the LNA is pulling the right DC voltages and currents at all terminals.

What are your input and output responses?

thanks,
I upload my circuit diagram ,where the same file is located:
https://www.edaboard.com/viewtopic.php?p=624055#624055
i think the parameters are probably not set right,but i can't find how to

Added after 18 minutes:

hi ,friends,can you leave you email or msn?thanks

my msn: ss_dengdeng(at)hotmail.com

nobody?

The circuit diagram you have uploaded is VERY cluttered and hard to read. Study the ADS help files for finding out how to avoid text overlap. One poster also asked for DC-voltages and currents. Do you have any control of these parameters? It's difficult to help you if you don't start by solving these issues.

i post the circuit again ,this one is clear.


yes ,i plot the DC voltage and current, decide the DC point ,but i'm not clear about the presentation of the DC point ,i can't see its effect.


thanks

your V_DC SRC1 has a value of -0.6V
isn't that wrong?

sorry,it is 0.6v,i'm wrong