geppei
Junior Member level 3
Hi everyone,
I am doing a 3.8G low power pre-amp
which also bandstop 900M,1.8M and 5.8M
everything is ok when using a network analyzer to check. Figure 1
(power = -10dBm), 15dB gain at 3.8G and there is already back off from P1dB
However, once i use Signal generator + spectrum analzyer to check the gain.
I realized there is also some "gain" for the noise floor too
my input was single carrier and power would be -10dBm(@1.9G). Figure 2
(the 3.8G is 2nd harmonics generated by my signal generator)
When i try to lower the carrier to -20~30dBm, the "noise floor gain" become less.
Figure 3
I am not sure whether it is a resonant or anything else.....
I am doing a 3.8G low power pre-amp
which also bandstop 900M,1.8M and 5.8M
everything is ok when using a network analyzer to check. Figure 1
(power = -10dBm), 15dB gain at 3.8G and there is already back off from P1dB
However, once i use Signal generator + spectrum analzyer to check the gain.
I realized there is also some "gain" for the noise floor too
my input was single carrier and power would be -10dBm(@1.9G). Figure 2
(the 3.8G is 2nd harmonics generated by my signal generator)
When i try to lower the carrier to -20~30dBm, the "noise floor gain" become less.
Figure 3
I am not sure whether it is a resonant or anything else.....
