Mu stability factors. How to find shortest distance from Gs / Gl to unstable region?
时间：04-04
整理：3721RD
点击：
I found formulas for computing mu / mu prime factors. Very useful:
But as i understand it is useful for Gs/Gl = 50 Ohm (center of Smith chart).
More interesting is to know distance between some arbitrary Gsource to nearest unstable point.
In details: if we have Gs / Gl, then their positions will move around smith chart for frequency sweep. Stability circles will be moving too. If for each frequency we can compute distance between Gs and nearest unstable region, then plot can be drawn.
I imagine negative distances can be used if Gs is inside unstable region, and this is distance to nearest stable point. Positive distances can be used if Gs is in stable region, and it is distance to nearest unstable point. Depending on what we going to achieve (oscillator or LNA /PA), we can see at which frequencies attention must be paid to Gs / Gl. For example, too small positive value alerts us that manufacturing tolerances can bring LNA to unstable region at some frequency, etc..
Is there any ready to use formulas for this purpose? I am sure it can be calculated, hope it is done already before.
Idea is: take Gs, take stability circle center, calculate distance D between Gs and stab.circle center. Calculate radius of stab circle R.
x=D - R, x is distance from Gs to circle. It can be inside/outside circle.
Gs/Gl - reflection coefficients.
But as i understand it is useful for Gs/Gl = 50 Ohm (center of Smith chart).
More interesting is to know distance between some arbitrary Gsource to nearest unstable point.
In details: if we have Gs / Gl, then their positions will move around smith chart for frequency sweep. Stability circles will be moving too. If for each frequency we can compute distance between Gs and nearest unstable region, then plot can be drawn.
I imagine negative distances can be used if Gs is inside unstable region, and this is distance to nearest stable point. Positive distances can be used if Gs is in stable region, and it is distance to nearest unstable point. Depending on what we going to achieve (oscillator or LNA /PA), we can see at which frequencies attention must be paid to Gs / Gl. For example, too small positive value alerts us that manufacturing tolerances can bring LNA to unstable region at some frequency, etc..
Is there any ready to use formulas for this purpose? I am sure it can be calculated, hope it is done already before.
Idea is: take Gs, take stability circle center, calculate distance D between Gs and stab.circle center. Calculate radius of stab circle R.
x=D - R, x is distance from Gs to circle. It can be inside/outside circle.
Gs/Gl - reflection coefficients.