Currently I am trying to use ratio of SNR's in/out, where:
For input noise, it is equal to 9.1186f sq v/hz:
**** resistor squared noise voltages (sq v/hz)
element 0:r3
rs 9.1186f
For output noise, it is equal to 433.9253f sq v/hz:
**** total output noise voltage = 433.9253f sq v/hz
Hence, the NF which I get at the moment from the testing circuit is:
= 10log(SNR in/SNR out)
= 10log(9.1186f/433.9253f)
= -16.77dB
I am not sure why I get negative value. Or how can I add signal gain to obtain the NF?