![]() Diagram of R S + jX S = R L - jX L.įor this condition, the energy transferred from the source to the load is maximized. It is well known that, to get the maximum power transfer from a source to a load, the source impedance must equal the complex conjugate of the load impedance, or:įigure 2. This can be valid for contingencies such as RS-485 lines, between a PA and an antenna, between an LNA and a downconverter/mixer, and so forth. A Quick Primerīefore introducing the Smith chart utilities, it would be prudent to present a short refresher on wave propagation phenomenon for IC wiring under RF conditions (above 100MHz). Fundamentals of impedance and the Smith chart. They can also help the designer with such tasks as optimizing for the best noise figures, ensuring quality factor impact, and assessing stability analysis.įigure 1. Of course, matching for maximum power transfer is not the only thing we can do with Smith charts. Topics addressed include practical illustrations of parameters, such as finding matching network component values. The primary objectives of this article are to review the Smith chart's construction and background, and to summarize the practical ways it is used. Smith chart: Upon which this article concentrates.In short, this is for the super-specialist. Instinct: This can be acquired only after one has devoted many years to the RF industry.Manual computations: Tedious due to the length ("kilometric") of the equations and the complex nature of the numbers to be manipulated.In addition, circuit-simulation software is not pre-installed on computers, unless they are dedicated to such an application. ![]() They also need the expertise to find the useful data among the tons of results coming out. Designers have to be familiar with the multiple data inputs that need to be entered and the correct formats.
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