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https://designers-guide.org/forum/YaBB.pl Design >> RF Design >> Matching problem https://designers-guide.org/forum/YaBB.pl?num=1182783487 Message started by jefkat on Jun 25th, 2007, 7:58am |
Title: Matching problem Post by jefkat on Jun 25th, 2007, 7:58am Hi guys, I have a resistor capacitor parallel combo (100ohm || 8pF). I have to match it to 100 ohm with a return loss of atleast 19dB from 1M to 400M. Its a challenge. Can anyone float an idea here please ? What are the theoretical limits in such cases ..any clues?? hope to hear some wisdom :-) Cheers Shaf |
Title: Re: Matching problem Post by mg777 on Jun 25th, 2007, 9:33am Where does the 19 dB come from? Is this for pulse transmission? Off the top: the bandwidth range 1:400 is way too high, in fact the 8 pF has a 100 Ohm reactance only at 200 MHz. So you're probably looking at 100 MHz to 400 MHz, or a Q close to unity. For starters, try a series inductor of 10,000*8e-12 = 80 nH, which also gives a resonance in the right range. Or fix the resonance and fiddle the Q. If you want a tighter performance, try a higher order Chebyshev LC ladder. But it's not worth the effort, I think. M.G.Rajan |
Title: Re: Matching problem Post by jefkat on Jun 25th, 2007, 11:59pm yes ,Its about pulse transmission.! Thanks for your input. |
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