jutlwj
Newbie level 6
I designed a LNA circuit based on BGU7003 as you can see in the attachment. The simulation results at 1279MHz and 1576MHz are also shown in the attached image. I then injected single tone of 1279MHz and 1576MHz respectively and tried to see the results on the spectrum analyzer. Then the weird thing happened. I saw some signals with unexpected frequencies as you can see in the attached image. It looks something like resonance. Did anyone see this kind of phenomenon before? What are these unexpected signals and where are they from? Is it because the gain of LNA is too high or there are some noises inside the power or ground to the LNA? I have never seen this before so it really confuses me. Could anybody have a look and help? Thanks.