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HMC3716 input sensitivity

Hello everybody,

I plan to use the HMC3716 in a PLL circuit for an oscillator with poorly specified output power.

Are there more detailed informations available on the input sensitivity of the HMC3716? The minimum input power given in the datasheet says -10 dBm, but other PFDs I used (e.g. ADF4002) would still work at lower input powers than nominal in a certain frequency range.

Regards, S. Fuchs

  • Hi,

    The min/max sensitivity from the spec table is best to follow since these numbers have been measured and verified at test. But yes the min/max spec in the datasheet applies to the full frequency range, and as a rule of thumb the min sensitivity of PFD inputs decreases along with frequency - hence we normally give a TPC plot of the sensitivity across frequency (like the ADF4002 you mentioned) but this is absent from the HC3716 datasheet.

    I had a look and wasn't able to find any sensitivity data for the HMC3716 or HMC439, so this is something you would have to test yourself. What frequency is your signal? If it is >=1GHz then I do not think you would have much margin to operate outside of datasheet spec. If it is lower than 100MHz then you would need to pay attention to the slew rate to ensure it does not drop too low i.e. by using a square wave input. The HMC704 datasheet gives some explanation on the slew rate requirements at low frequencies, but again unfortunately we have limited data on an actual number for the min slew rate required for the HMC3716