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I need to generate a signal on 433.92 MHz starting from a 13.56 crystal. Using a string of 5 doublers seems too much like hard work. Anyone know an easier way?
433MHz sounds like ISM. Are you stuck with the 13.56MHz crystal? If it is for ISM, there are many ICs out there which do the bulk of the work for you (ADI, Radiotronix, RFM, HopeRF, etc).
If you just need the clock, look at IDT or Maxim for clock generators (these have built-in PLLs and VCOs to generate your frequency from the xtal/clock input).
Yeah, I agree that 5 doublers in a row is a bit much. Seems like a synthesizer is the best way, but that's not trivial either. For example, using Fujitsu MB15E03 chip has lots of stuff on it, but you still have to program it serially and you have to hang a VCO off of it too. That's pretty typical of the general purpose synthesizer ICs. Maybe there is a 433MHz transmitter chip out there that suits?
I would do it with a 48.21333 MHz 3rd overtone crystal, picking off third harmonic with low value inductor on collector of colpitt oscillator.
Need a two pole filter (osc collector coil + input coil to active tripler) on third harmonic oscillator output (144.64 MHz) then single active tripler to 433.92 MHz. Should have two pole filter on 433 MHz output to ensure reduction of fundament and sixth harmonic.
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