LMX2571EVM: LMX2571EVN

Sungchan Choi

Prodigy 10 points

Part Number: LMX2571EVM
Other Parts Discussed in Thread: LMX2571

Tool/software:

Hello,

I have two questions as to LMX2571EVM board.

According to the graph in page 18 of User Guide document, it seems that -144dBc/Hz of phase noise is supported when CHDIV1 is set to 4 and CHDIV2 is set to 64. Are CHDIV1 and CHDIV2 settable through SW command? Are there any restrictions by setting those two parameters like that?
It seems that the board supports FM signal generation. Then is it possible to generate FM signal of +/-75kHz deviation, which is the requirement of FM broadcast signal?

Thanks in advance for your help.

Regards,

Sungchan

2 months ago

0 Noel Fung 2 months ago

TI__Guru* 89540 points

Hi Sungchan,

Both CHDIV1 and CHDIV2 are configurable.

75kHz frequency deviation is not possible using the internal VCO, you have to use external VCO and modulate the VCO.

Please note, LMX2571 does not support analog modulation directly, modulation is achievable by changing the PLL's fractional numerator. This operation requires extensive processor support. See below appnote for details.

www.ti.com/.../snaa309

0 Sungchan Choi 2 months ago in reply to Noel Fung

Prodigy 10 points

Dear Noel Fung,

Thanks for your answers, much appreciate.

Regards,

Sungchan

Clock & timing

Clock & timing forum

LMX2571EVM: LMX2571EVN