I'm doing a work which use AD9516's LVPECL output as ADL5385's local oscillator signal. Since LVPECL has very high odd harmonic components, i am wondering if I need a LPF to filte those harmonic. I saw the datasheet of ADL5375 which said;
Care must be taken to adequately suppress the harmonics of the LO signal from the PLL. A large third harmonic on the LO degrades the quality of the quadrature generation inside the IQ Modulator.
But situation is different for ADL5385 as its LO will be divided by 2 inside the chip, so I guess we don't need to filt the LO harmonics for ADL5385.
does anyone here can confirm this?