Converting S to Y matrix

[contau]

Hi, I have a problem about converting S to Y matrix of 2SC3355 transistor. The converted Y matries are below:

**VCE= 10 V, IC= 20 mA, ZO= 50:


200MHz: y(1,1) = 0.0079 + 0.0028*i
y(1,2) = -0.0001 - 0.0008*i
y(2,1) = 0.1168 - 0.2403*i
y(2,2) = 0.0004 + 0.0011*i

400Mhz: y(1,1) = 0.0095 + 0.0032*i
y(1,2) = -0.0001 - 0.0014*i
y(2,1) = 0.0241 - 0.1514*i
y(2,2) = 0.0011 + 0.0041*i

600MHz: y(1,1) = 0.0087 + 0.0042*i
y(1,2) = -0.0001 - 0.0024*i
y(2,1) = 0.0024 - 0.1034*i
y(2,2) = 0.0002 + 0.0061*i


**VCE= 10 V, IC= 40 mA, ZO= 50:


200MHz: y(1,1) = 0.0312 + 0.0182*i
y(1,2) = -0.0010 + 0.0012*i
y(2,1) = 0.3420 - 0.4062*i
y(2,2) = 0.0154 + 0.0159*i


400MHz: y(1,1) = 0.0091 + 0.0036*i
y(1,1) = -0.0002 - 0.0014*i
y(2,1) = 0.0175 - 0.1536*i
y(2,2) = 0.0010 + 0.0047*i

600MHz: y(1,1) = 0.0084 + 0.0039*i
y(1,2) = -0.0002 - 0.0024*i
y(2,1) = -0.0019 - 0.1038*i
y(2,2) = 0.0004 + 0.0062*i


But in Ic =40mA, VCe = 10V at 200Mhz:
y(1,2) = -0.0010 + 0.0012*i --> This indicates the inductance feedback.

y(1,1) = 0.0312 + 0.0182*i --> y(1,1) at 200Mhz is quite larger than y(1,1) at 400MHz and 600MHz with same Ic current.

I don't understand why
Please interpret for me to understand!

2SC3355 datasheet: https://www.electro-tech-online.com/custompdfs/2013/03/2sc3355.pdf

 

[RCinFLA]

When you are dealing with a leaded TO92 plastic package it is all about lead inductance. They don't specify exactly how much lead lengths they are leaving when making their S parameter measurements. Things appear to be going through self resonance between 400 and 600 MHz.