Hi, I'm trying to understand the results from a very simple sim:
source - gain block - port
The gain block is set with NF=0.01dB, G=10dB and reverse isolation=100dB
Then what I'm expecting to see at the amp input, for a 1Hz channel, is:
from source: -173.826dBm
from the amp: -173.826dBm from the port -100dB (RI) = -273.86dBm
However I get from the amp -167dBm
Is there something I'm missing
Could you please explain?
Regards
Fred
source - gain block - port
The gain block is set with NF=0.01dB, G=10dB and reverse isolation=100dB
Then what I'm expecting to see at the amp input, for a 1Hz channel, is:
from source: -173.826dBm
from the amp: -173.826dBm from the port -100dB (RI) = -273.86dBm
However I get from the amp -167dBm
Is there something I'm missing
Could you please explain?
Regards
Fred
You will see that the -167.8 dBm number at the amplifier input is due to 4 pieces of noise spectrum. Three are from the amplifiers noise correlation matrix entries and one is from the output port noise coming through the reverse isolation of the amplifier. The noise from the output port is exactly -273.826 dBm as you predict. However, the dominant -167.809 dBm noise component is internally generated in the amplifier and appears at the amplifier input.
Noise correlation matrices are non-trival. For more information please see the paper called, "Computer Aided Noise Analysis of Linear Multiport Networks of Arbitrary Topology", WEEE Transactions on Microwave theory and Techniques, Vol. MTT-33, No. 12, Dec 1985, by Vittorio Rizzoli and Alessandro Lipparini.