A low-noise preamplifier is to be driven from a 10-Ω source. Data supplied by the manufacturer specify Vn and In at the operating frequency as
a. Determine the input-transformer turns ratio to provide optimum noise performance.
b. Calculate the noise figure for the circuit using the transformer of part ‘‘a.''
c. What would be the noise figure with the preamplifier directly coupled to the 10-Ω source?
d. What would be the SNI factor for this circuit?