Scott wrote:



I want to build a low pass filter for 1296 and have scaled a design out
of the handbook. I would like to use chip inductors and chip capacitors
for the filter. I was looking at thin film chip inductors (Digi-Key)
and they list the self resonant frequency. For an inductor passing
1296, what should the minimum self resonant frequency be? Is 10 GHz
enough? The filter is a 5 element Chebyshev Low Pass Filter, inductive
input (3 coils in series with a cap at each inner junction to ground),
Fco=1290 MHz, F-20dB=2600 MHz. Any other component specs I need to be
aware of?

Scott
N0EDV

10Ghz would be *almost* an order of magnitude away from the frequency of
interest. That should be more than sufficient. The higher the self-resonant
frequency, the less parallel capacitance is involved which makes "trimming"
the filter less involved. At this frequency your capacitors are going to be
pretty small. Parasitic capacitances, such as in the inductor, can make
things look pretty screwy in a big hurry.

tim ab0wr