S-Parameter Simulations > S-Params., Noise Fig., Gain, Stability, Circles, and Group Delay

Description

This simulates the S-parameters, noise figure, stability, and group delay of any two-port network, versus frequency. You may use it with an S-parameter data file, or with a nonlinear amplifier model.

Needed to Use Schematic

Any linear or nonlinear model, including measured S-parameters

Main Schematic Settings

Frequency sweep range

Data Display Outputs

SP_NF_GainMatchK.dds, "NF, Gain, Stab. Fact., Matching" page:

• Minimum noise figure and noise figure with 50 ohm terminations versus frequency
• dB(S21), maximum available gain, and associated gain (when the input is matched for NFmin and the output is then conjugately matched), versus frequency
• Stability factor, K, and geometric stability factors, mu_source and mu_load versus frequency
• Smith chart with traces of the optimal source reflection coefficients for minimum noise figure, source and load stability circles, and the following reflection coefficients (gammas) at a frequency selected by moving a marker:
  • Gamma source for minimum noise figure
  • Gamma load for maximum power gain when input is terminated for minimum noise figure
  • Gamma source for simultaneous conjugate match (without regard to noise)
  • Gamma load for simultaneous conjugate match (without regard to noise)
• Listing columns of data corresponding to the frequency point selected by moving a marker:
  • S-parameters, dB
  • Maximum available power gain, dB
  • Minimum noise figure, dB
  • Sopt for minimum noise figure in polar coordinates and in magnitude and phase
  • Zopt for minimum noise figure
  • Associated power gain in dB, if the input is matched for minimum noise figure and then the output is matched for maximum power gain
  • Corresponding load impedance for associated power gain
  • Source and load impedances for simultaneous conjugate matching (without regard to noise)
  • Stability factor, K

SP_NF_GainMatchK.dds, "Gain, Noise, and Stability Circles" page:
All at one frequency selected by moving a marker:

• Stability factor, K, and source and load stability circles. Note that the Smith chart size is fixed, so if the stability circles are far outside the Smith chart, they will not be displayed. If you change the Smith chart scaling to Auto Scale, the circles will be visible.
• Available gain and noise circles
• Minimum noise figure, source impedance (Zopt) required to achieve this noise figure, and the optimal load impedance for power transfer when the source impedance is Zopt, as well as the transducer power gain with these source and load impedances
• Maximum available gain, and the source and load impedances required for simultaneous conjugate matching (only valid if K>1), and the corresponding noise figure
• Noise figure, transducer power gain, and optimal load impedance if the source impedance is chosen arbitrarily by moving a marker (GammaS) on a Smith chart. This is useful if you must make some compromise between noise and gain, or if you need to avoid an unstable region.
• Power gain circles, on a different Smith chart
• Transducer power gain, optimal source impedance, and corresponding noise figure, if the load impedance is chosen arbitrarily by moving a marker (GammaL) on a Smith chart. This is useful if you need to avoid an unstable region.

SP_NF_GainMatchK.dds, "S Parameters, Group Delay" page:

• S11 and S22 on Smith charts, also with a circle of constant VSWR
• S21 and S12 (linear units) on polar plots
• dB(S21) and dB(S12) on a rectangular plot
• Group Delay in seconds, versus frequency.

Note This plot may be jagged if measured S-parameter data is simulated, and the number of measured points is small.

Schematic Name

SP_NF_GainMatchK

Data Display Name

SP_NF_GainMatchK.dds