Gain of multiplier FET at target frequency, can it be <1 for target frequency?

Status
Not open for further replies.
T

Terminator3

Advanced Member level 3
Joined
Feb 25, 2012
Messages
802
Helped
71
Reputation
142
Reaction score
63
Trophy points
1,308
Activity points
9,027
For example, we double some frequency. At F0 gain is >3, and at 2*F0 it is <1. I thought that high gain at F0 is enough, because we get clamped wave at F0, wich contains 2F0 harmonics. But from simulations, i see, that performance not as good as i expected. Even no gain!!! after doubling. If use the same device at lower frequency and n*F0 is looks pretty well.
 

Are you suggesting that you expect the gain of a FET to be the same when used as an amplifier or as a multiplier? In the old days we used to have to generate 50W+ at VHF frequencies to get 1 W at UHF with a load of multipliers, its the way of the world.
Frank
 
I can't understand why harominc is attenuated more, than at lower frequency. Is it some kind of loss inside FET? Maybe it's parasitics works as block for harmonic RF? When i double relatively low frequency, it's output is high, almost 0dBm. Gain at F0 is about 3, and at 2*F0 is around 1. When i double higher frequency, the output is -40..-50dBm, gain at F0 is still 3, and i use similar design procedures. Gain is lower than 1 for target frequency, so i thought maybe it is related somehow.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…