A 3-stage amplifier is to have an overall noise temperature no greater than 75 K. The overall gain of the amplifier is to be at least 40 dB. The amplifier is to be built by adding a low-noise first stage to an existing amplifier with existing characteristics as follows: The first stage has 20 dB power gain and a noise figure of dB. The second stage has 15 dB power gain and a noise figure of 6 dB.
What is the unitless gain of the first stage?
b. What is the overall noise factor of the amplifier?