This is for school. I'm trying to match a single transistor 1GHz amp output stage (common emitter) with a double-stub tuner. A 10mm-20mm TL (length L2) runs between the collector and 1st stub, then 1/8-wavelength TL between the stubs, then some length connects to a chip cap (DC block; 0.1uF), then ~10mm to the SMA connector.
Zout = 143.14 @ -35.14deg
--> y_out = 0.286 + j0.201 (normalized output admittance to 1/50Î©)
wavelength = 166.99mm
Question is really about Smith chart usage, but I know you techies like details ;) .
I've rotated y_out towards the load, and rotated the g=1+jb circle towards the generator (it's at the top of the chart, now), and now have to follow constant real admittance lines to intersect that circle. Do I go clockwise or counter-clockwise? My textbook [Pozar] and a few online examples indicates that I can go either way; common-sense tells me to go clockwise, but I've always matched input circuits (wrt. a load), not output circuits (wrt. a source).
scan of Smith chart solutions with L2 = 10mm, 15mm, and 20mm:
[75dpi; 1 MB] or [300dpi; 15 MB]
Question pertains to the blue arrows, between the A's and B's, and the green arrow (on the g=1+jb circle), between the C's and g=1.
Related, how do I get stub length?