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Do we need to suppress ADL5385's LO harmonic components?

Question asked by plkmn3 on Apr 8, 2013
Latest reply on Apr 12, 2013 by plkmn3



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?