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HMC1044 SPI Clock freq and RF Behavior


I am using HMC1044 in one of my application. Using STM32F417 controller to configure HMC1044 through its SPI. 

I tried with 1MHz to 20Mhz as SPI clock but not able to configure HMC1044. What is the supported SPI clock frequency ? in data sheet I see its 20ns minimum clock time which is (50MHz) is this true?

And for every band selection I do, Filter behavior is same. 

RF behavior with default Band-15:

With the default band-15 configuration I am unable to see the required filter performance.

I am feeding -20dBm as in put level, fed frequencies from 900MHz-4GHz, but filter output is not uniform in pass band, that is at 1.2GHz its giving -50dBm at 2GHz its giving -48dBm.

Variation is not at all linear in the pass band. Can you share its behaviors Gain vs Frequency for different bands. 




  • Your SPI clock frequencies should be OK.

    Are you following the SPI protocol (clock phase, polarity, etc.) outlined on page number 14 of the datasheet?  Note that bits should be clocked in MSB first, with the 9 data bits clocked in first, followed by the 4 register bits, and finally the 3 Chip address/ID bits which are 0b110.

    If you're still having trouble programming the corners, would you mind posting a screen shot with an oscilloscope of what you are writing on the SPI bus?   

  • Hi,

    Yes i tried SPI protocol according to the details given in datasheet.And i am able to see the SPI clock , master out , and SEN in oscilloscope properly.And SPI is working fine.

    Problem is resolved with following modification:

    I was using single ended input and output. Expected behavior is observed with input and out connected to with IN_N and OUT_N  respectively.

    Thanks for your support


  • Ah yes, the rejection is a bit different depending on if you are using the part single-ended or differential.  The characteristics of this is shown in the datasheet.

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