xiaowenrun
Junior Member level 3
Hello everyone
I am testing an LNA. A buffer is added since the LNA cannot drive a 50Ω load directly. However, the buffer adds up to the noise measurement result. I am trying to subtract this influence according to an equation shown below.
Flna + Fbuf/Alna^2 = Fsys
where Flna is the noise figure of the LNA, Fbuf is the noise of the buffer, Alna is the voltage gain from the signal source to the output of the LNA, Fsys is the noise of the whole circuit (LNA+buffer). Here Alna considers the source resistance.
Is this right or wrong? I found a 0.24dB between the calculated and simulated results (3.26dB).
I found an equation describing the relationship between the noise of the cascaded stages and the whole system. But the available power gain is needed and I do not know how to measure it.
Thanks in advance.
I am testing an LNA. A buffer is added since the LNA cannot drive a 50Ω load directly. However, the buffer adds up to the noise measurement result. I am trying to subtract this influence according to an equation shown below.
Flna + Fbuf/Alna^2 = Fsys
where Flna is the noise figure of the LNA, Fbuf is the noise of the buffer, Alna is the voltage gain from the signal source to the output of the LNA, Fsys is the noise of the whole circuit (LNA+buffer). Here Alna considers the source resistance.
Is this right or wrong? I found a 0.24dB between the calculated and simulated results (3.26dB).
I found an equation describing the relationship between the noise of the cascaded stages and the whole system. But the available power gain is needed and I do not know how to measure it.
Thanks in advance.
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