[time-nuts] fast freq. synthesis schemes

[Lux, Jim (337C)]

> Behalf Of Luis Cupido
> Sent: Wednesday, October 14, 2009 3:25 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] fast freq. synthesis schemes
> 
> Hi,
> 
> I'm looking for the schemes used on the
> frequency synthesizers that change frequency
> in few microseconds time (or less)
> at microwaves lets say circa 12-18Ghz)
> Obviously with some resolution (let's say 100Khz step
> or in that order)(otherwise it would
> be a trivial exercise in the BW of the PLL loop filter)
> 

What range does it need to tune over? The whole 12-18, or some smaller section?

You could use a fixed oscillator, multiply it up, and then mix the output of a DDS, perhaps also multiplied.

1 GHz works nice as a clock to a DDS, and as a basis for the "fixed" part.