How to multiply frequency

Discussion in 'The Projects Forum' started by dwf_90, Aug 13, 2015.

  1. dwf_90

    Thread Starter New Member

    Aug 13, 2015
    Is it possible to take a 400hz signal and multiply it to 40Mhz?
    How can this be achieved and is there a packaged device that can be purchased to achieve this as easy as possible? Thx
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    the least componants would be a 400 mhz pll locked to the 400 hz.
    multiplying by that much would take quite a few stages. frequency multiplycation is done by introducing distortion to the wave, that creates more harmonic energy. then you filter out the desired harmonic, amplify and select the next harmonic. usually harmonics from second to ninth per stage. any frequency modulation would be multiplyed by the same ammount, as well as drift of the origional signal. FM radio stations used this method to get the 150 to 300 khz deviation.
    Last edited: Aug 13, 2015
    dwf_90 likes this.
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    Using frequency multiplication, if the frequency of the 400Hz signal shifts by just one Hz from e.g. 400Hz to 401Hz, the frequency of the locked 40Mhz signal would shift from 40.000MHz to 40.100MHz, a whopping 100,000Hz shift.

    Usually, you start with a stable 40MHz reference oscillator, and use frequency division to create a stable 400Hz signal...
  4. DickCappels


    Aug 21, 2008
    A frequency synthesizer -a PLL and a frequency divider would do it. Another approach would be to have successive stages of frequency multipliers (non-llinear amplifiers with the outputs tuned to a harmonic of the input).
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    What sort of signal? Analogue, digital, constant-amplitude, frequency-modulated ....?
    Why would you want to do this?
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
    A 4046 IC will enable frequency multiplication up to about 1.3 M HZ, not sure of how many stages would be required. I used it to convert 60 Hz to 50 Hz by phase locking 300 Hz to 60 Hz, then dividing 300 down to 50 Hz for master clocks. I know of no ICs capable of phase locking to 40M Hz.
  7. crutschow


    Mar 14, 2008
    Generating 40MHz from 400Hz is a very strange requirement.
    What is this for?
    GopherT likes this.
  8. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Good question. If something needs to be done and can be done, there is generally a well-known technique (or even a specific chip) to do it. I have never heard of multiplying frequencies to such a level before so, as your question suspects, there is likely another way (correct way or possible way) to achieve the OP's end goal.
  9. wayneh


    Sep 9, 2010
    The solution is called a radio transmitter. 400Hz is in the audio range, so it's no problem for a standard microphone or line-in signal. Finding a 40MHz transmitter shouldn't be too hard. Baby monitors and old cordless phones were at 49MHz, if I recall.

    Now, this isn't truly "multiplying" by 100,000 as implied by the question. But without more explanation of what is needed, it seems as valid a solution as any other.