frequency multiplication

[spuffock]

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?

 

[Nigel Goodwin]

You could try two quadruplers and a doubler, but if you want easier choose a higher crystal.

Obviously a less 1960's technique would be to use a PLL and give it adjustable frequencies.

 

[languer]

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).

 

[RadioRon]

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?

 

[languer]

That's what I was referring to. If you are looking at operating on the ISM band a few suggestions follow:

• RCT-433-AS => SAW-based ASK/OOK transmitter (does not require external crystal/reference)
• TR3000 => SAW-based ASK/OOK transceiver(does not require external crystal/reference)
• TRC105 => PLL-based FSK/ASK/OOK transceiver(does require external crystal/reference - you could use 13.56MHz XTAL, although recommended is 12.8MHz)
• RFM12B => PLL-based FSK/ASK/OOK transceiver(does require external crystal/reference - you need a 10MHz XTAL)
• Other manufacturers with similar or better devices => Analog Devices, Maxim/Dallas, Microchip ...

If what you need is a frequency reference of 433MHz, based on you 13.56MHz source then something as follows would be a recommendation:

• Analog Devices => Integrated PLL/VCOs (e.g. ADF4360-7)

 

[RCinFLA]

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.