one element matching - RF Cafe Forums
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Post subject: one element matching Posted: Wed Aug 16, 2006 6:13 pm
Joined: Fri Apr 21, 2006 10:34 pm
hi...if i have a parallel RC load (i.e. a BJT input impedance) where R is almost 50 Ohms is it possible to use just a series inductor to match to a 50 Ohm source? i can see how just using a shunt inductor this can be accomplised but i'm not sure if using a series inductor will do the match. if it can be done, can someone briefly explain how? thanks
Post subject: Posted: Wed Aug 16, 2006 11:09 pm
Joined: Tue Apr 18, 2006 10:40 pm
yes, you can do it. but it seems like you're mixing up the definitions; if you know or found out that your IMPEDANCE is something like 50-jXc, then that means that is 50 in series with Xc and so when you do your analysis by hand or CAD you need to have a series RC model and not parallel RC model.... of course, if you need to think in parallel you can always convert to admittance. on the other hand, if your admittance was 50-jXc then you're on the right track but this value would be odd for a transistor because that means that your transistor size is giving, in simple form, an rpi value of 1/50, which as far as I can know can't be possible.