Maker Pro
Maker Pro

RF filter question



Jan 1, 1970
I have a 50% square wave at 1.65V p-p into 50 ohms, 50MHz to 200MHz. Now, the
first harmonic of the 50MHz is 150MHz.
How do I design a filter that will give me a sine wave 50MHz to 200MHz, with 1dB
flatness across the band, with at least +7dBm output? I was thinking of a low
pass filter, but that was when the frequency was limited from 33 to 45 MHz, it
was fairly easy to get a sine wave.
The only thing I can see is to make several filters and switch them according to
the frequency. I am not worried about the phase relationship between the square
and sine. And I've used lots of equipment that 'thunks' when relays are being
kicked in, so I know that using relays for things like this is not unheard of,
but usually for attenuators.
In case anyone is wondering, I'm recycling the clock oscillator from a PC
motherboard and sticking it in a case.
Look here for the basic, incomplete first try.

I now have a few more MBs ready on the chopping block, and I have some Cypress
chips that have more resolution than the winbond.