LMX2572: OSCin requirements

Austen Fogarty

Part Number: LMX2572

Hi,

I'm planning on using the LMX2572 as a local oscillator for a X band radio. Are there any requirements for the input oscillator such as phase noise, jitter and accuracy? The datasheet only mentions to ensure a high slew rate. I need to determine whether it would be accepable to use an FPGA for the OSCin, if not, what quality of external oscillator I would need for my application and to meet the output specs in the datasheet.

Thanks,

Austen

6 months ago

0 Noel Fung 6 months ago

TI__Guru** 122470 points

Hi Austen,

What is your phase noise requirement to the output of LMX2572?

0 Austen Fogarty 6 months ago in reply to Noel Fung

Prodigy 40 points

Hi Noel,

I don't have an exact number for the phase noise, we would like it to be as low as possible. Does the phase noise on OSCin translate throught to the VCO output?

Thanks,

Austen

+1 Noel Fung 6 months ago in reply to Austen Fogarty

TI__Guru** 122470 points

Hi Austen,

Right, the reference clock noise will carry forward to the output of the synthesizer, so the noise of the reference clock is matter, especially if you are looking for the lowest possible phase noise from the synthesizer.

Suggest use crystal-based oscillator (XO) as the reference clock. There are many XO in the market, again, the selection depends on your system requirement.

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LMX2572: OSCin requirements