1)Assume you have a two stages low noise amplifier. The first stage closest to the input has a 10 dB gain and a 1 dB noise figure. The second stage has a 10 dB gain and a 5 dB noise figure. What is the overall noise figure for the amplifier and what is the equivalent noise temperature of the 2-stage amplifier Te?
2)If at the input of the 2-stage amplifier of the previous problem the signal to noise ratio is 6 dB and the source equivalent temperature is Ts=200K (so you can assume an input noise power of KTsB), what's the signal to noise ratio at the output of the amplifier? Repeat the same problem for Ts=290K. Hint: the two answers are different, and the SNR is kept the same in both cases.
3)Assume you have a receiver with an overall noise figure of 23 dB and a bandwidth of 1 MHz. Assuming the minimum acceptable SNR at the output of the receiver is 6 dB, estimate the minimum detectable signal level in dBm at the receiver input.