[time-nuts] Low noise frequency multiplication
stephan at rrsg.ee.uct.ac.za
Thu Mar 1 08:48:49 EST 2007
It seems there are indeed many ways to kill a cat. What happens to the
close-in phase noise using this method?
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of SAIDJACK at aol.com
> Sent: 01 March 2007 03:39 PM
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] Low noise frequency multiplication
> In a message dated 2/28/2007 15:20:56 Pacific Standard Time,
> stephan at rrsg.ee.uct.ac.za writes:
> It describes a way in which an analogue odd-order frequency multiplier
> be built cheaply with superior noise characteristics. This circuit that
> described is really simple and quite ingenious. Unfortunately, I would
> to multiply by 10 (an even number) so I still need a way to at least
> multiply by 2. Commercial low-noise multipliers are in general much more
> expensive than my OCXO. So now I am curious if there is an easy and
> way to get a 10MHz sine up to 100MHz without degrading the phase noise.
> Hi Stephan,
> one way to do it is using a DDS, say one of the new 1Gs/s 14-bit DAC
> from Analog Devices:
> bring the 10MHz up to 1GHz using a 1 to 100 PLL and a low-phase noise 1GHz
> VCO or 1GHz crystal (these 1GHz low-jitter crystal Oscillators have
> been advertised).
> Then use the DDS to generate 100MHz at 1Gs/s.
> Noise floors of <-155dBc/Hz can be easily achieved with a good DDS. You
> need is a low pass at around <400MHz to remove aliases etc.
> One advantage of this is that you can generate essentially any frequency
> <1Hz steps up to about 400MHz (without having a frequency-dependent noise
> floor on the DDS output).
> You could get a DDS eval board from Analog to do this.
> This is essentially what the Jackson-Labs FireFox Synthesizer does.
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