domingo, 27 de junio de 2010

Types of S-parameters

When we are talking about networks that can be described with S-parameters, we are usually talking about single-frequency networks. Receivers and mixers aren't referred to as having S-parameters, although you can certainly measure the reflection coefficients at each port and refer to these parameters as S-parameters. The trouble comes when you wish to describe the frequency-conversion properties, this is not possible using S-parameters.

  • Small signal S-parameters are what we are talking about 99% of the time. By small signal, we mean that the signals have only linear effects on the network, small enough so that gain compression does not take place. For passive networks, small-signal is all you have to worry about, because they act linearly at any power level.
  • Large signal S-parameters are more complicated. In this case, the S-matrix will vary with input signal strength. Measuring and modeling large signal S-parameters will not be described on this page (perhaps we will get into that someday)
  • Mixed-mode S-parameters refer to a special case of analyzing balanced circuits. We're not going to get into that either!
  • Pulsed S-parameters are measured on power devices so that an accurate representation is captured before the device heats up. This is a tricky measurement, and not something we're gonna tackle yet.

Publicado por: Jahir Alonzo Linares Mora C.I: 19769430 CRF

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