LNA Design Uses Series Feedbackto Achieve Simultaneous Low Input VSWR and LowLNA Design LNA Design Uses Series Feedback to Achieve Simultaneous Low Input VSWR and Low Noise By Dale D. Henkes Sony PMCA he noise figure of a Zsource Zload Zin Zout single stage transistor amplifier is a function of the impedZg ance applied to the input Transistor/ terminals of the transisInput Output Two-Port tor. This impedance, ZL matching matching S11 S12 called the source impednetwork [ S21 S22 ] network ance, is shown in Figure 1 as Zsource. Typically the source impedance that produces a conjugate GS , GOpt GL Gin Gout match to the input impedance of the transistor (Zin) is not the same s Figure 1. The generalized analytical form of the low noise amplifier. impedance as would be required to produce a minimum noise figure for the amplifier. The overall system performance is proba……