LMX2572: Ramping mode vs phase management

daniele sassaroli

Part Number: LMX2572

Dear Sirs,

i'm studing the possibility to use the LMX2572 such as CW generator.

In my design, I must generate at fixed frequency or stepped frequency.

In the second case, the frequency of the output signal is not constant but
could be changed in up or down with a step of 2 MHz.

I've read the Ramping function of the LMX2572 and I'm verifing this
function for my application.

The questions are:

- Is it possibile to set 2 MHz step when using the Ramping mode, in manual mode;

- When the output frequency of the LMX2572 go from F0 to F0+2Mhz, after rampingclk
signal, is there a specific phase relation between the F0 and F0+2MHz? For example,
when the frequency of output signal change between F0 and F0+2MHz the phase
as constant or it has a jump?

I'm looking forward to hearing from you

Best Regards,
Daniele Sassaroli

over 5 years ago

0 Vibhu Vanjari over 5 years ago

TI__Genius 11900 points

Hello Daniele,

Yes the 2 MHz steps are possible with manual ramp.

I do not understand your question about the phase relationship. You cannot compare the phase of two different frequencies correct?

Thanks,

Vibhu

0 daniele sassaroli over 5 years ago in reply to Vibhu Vanjari

Intellectual 650 points

Hello Vibhu,

in the attached file you can see the question about the phase relation between the two frequency.

Best Regards,
Daniele Sassaroli

LMX2572_V10.pdf

0 Noel Fung over 5 years ago in reply to daniele sassaroli

TI__Guru** 117470 points

Hi Daniele,

I think the frequency change is not seamless. We change the N-divider in order to change the VCO frequency. As such, it takes some little time for the VCO to gradually switch to the new frequency.

Clock & timing

Clock & timing forum

LMX2572: Ramping mode vs phase management