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problem of hmc928lp5 evaluation board

Question asked by onlycflxzh on Jul 28, 2015
Latest reply on Aug 6, 2015 by kkaya

Hi,

   now, we are testing the evaluation board of HMC928LP5 phase shifter. We saw something strange. We tested it by using two tones(center at 2.08896GHz, 1MHz spacing). In the spectrum, we saw something spurs(repeated at every 24MHzaway from the carrier frequency) around the noise floor(see the figure1).

Because we are designing full-duplex cancellor, we are really care about the noise floor of system. It seems that those spurs limits the floor noise for a modulation signal(say LTE signal).

 

Is this normal for this phase shifter? why there are spurs? Can anyone help me? Thank you very much

 

These spurs are not IMD,(IMD is showed in Figure 2).

 

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Figure 1

 

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Figure 2

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