octave sparameter

I hv got one transistor with S parameter available for 10V 7ma & 10V 20ma. Can i take the center average from above for 10V 13.5ma as mentioned below?

VCE = 10V, IC = 7mA
Fre Mag Ang Mag Ang Mag Ang Mag Ang
100 .759 -43 16.992 148 .004 54 .896 -18

VCE = 10 V, IC = 20 mA
Fre Mag Ang Mag Ang Mag Ang Mag Ang
100 .57 -66 28.21 134 .00 46 .75 -28

for
VCE = 10V, IC = 13.5mA
Fre Mag Ang Mag Ang Mag Ang Mag Ang
100 .665 -55 22.60 141 .002 50 .823 -23

Yes, but you are not averaging correctly. You must treat the complex number has a whole, not interpolate the magnitude and angle separately:

1/2*[0.759*e^(-j*43*deg) + 0.57*e^(-j*66*deg)] = 0.651*e^(-j*52.9*deg)

You can also break it into real and imaginary parts, interpolate those separately, and get the same result.

Madengr,

Thanks for ur reply!
Can u give more details on how exectly u hv calculated?
Newbie to RF, Hence ur help required.

I just typed the equation into mathcad but matlab or octave will work too. The only problem is that most math packages do not return the results in polar form so you must use the angle() or arg() function to calculate the angle. This is basic math though not RF.

You can also use google:

1/2*(0.759*e^(-i*43*pi/180) + 0.57*e^(-i*66*pi/180))

http://www.google.com/search?hl=en&r...pi%2F180%29%29

Can we write the formula in Excel?
Or can we write small programme to do so?
Guidance in the matter is welcome.

I found polar to rectangular converter at this site

hxxp://www.daycounter.com/Calculators/Polar-To-Rectangular-Calculator.phtml

I converted to rectangular, then did addition & devided by 2. Once more converted from rectangular to Polar.
I got .65 -52.8deg. instead of 0.651 -52.9deg. by madengr in Mathcad. This is almost close. Very easy & simple.
Thanks to all for help & guidance!

I forgot to mention you can put the s-parameters in an MDIF file along with your bias variables. The simulator will then interpolate the s-parameters between data sets. You could have sets of data over several dimensions such as VGS, VDS, and temperature. Microwave Office and ADS both support this and I'm sure others do as well.

I am newbie & don't hv those expensive professional simulators. Hence for the time being this idea is not suitable for practical purposes. But good for my acedamic knowledge.