Can we adjust the signal phase generated by signal generator

[GDF]

I would like to generate a LO signal from signal generator. But I don't know
any kind of signal generator can adjust the signal pahse?

Anybody has the experience?

Thanks,

 

[biff44]

Re: Can we adjust the signal phase generated by signal gener

You can buy a vector modulator, with an I and Q control, and linearly generate any phase you want. You could buy a digital phase shifter where you can switch in different phase states with perhaps a 6 degree LSB.

In any case, you want to be careful that you have a signal generator with a "constant" phase. By constant phase, I mean if you actually watch the phase of the RF signal it does not make any sudden phase jumps, or walk its way around the phase chart. A lot of fractional N and DDS type synthesizers do not have a constant phase, but instead do the smaller frequency steps by walking the phase.

 

[madengr]

Re: Can we adjust the signal phase generated by signal gener

Some of the Agilent generators are phase continuous when switching frequencies. For instance set it for 1.000000000 GHz and observe the DC voltage on your phase detector. Then switch it to 1.000000001 GHz an observe the DC out of your detector. When it gets to where you want then set it back to 1 GHz. Crude method but it works.

You can also use a variable delay line. I don't know if they make them anymore but I have a Narda one with a crank handle that will give 360 degrees at 1 GHZ (If I remember correctly).

 

[biff44]

Re: Can we adjust the signal phase generated by signal gener

Yeah, I have a bunch of those. Pretty essential if you are doing some sort of manual phase noise or carrier nulling tests. You see them on ebay every once in a while.