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Can HMC1033 be used with Mixer LT5512


I would like to know if the PLL HMC1033 could be used with LT5512 Mixer.

What is the output impedance of HMC1033 and how is the matching circuit with LT5512. Should I go for differential or single-ended I/O ?

Thanks in advance,


  • This should work just fine.  I would start with a single ended interface due to the small LO requirements of the LT5512.  

    Refer to figure 20 of the HMC1033 datasheet for the unused single ended port.  Refer to Figure 6 of the LT5512 datasheet (the 100 ohm external makes is in parallel with the  2 parallel 200 ohms resistors internal to the LT5512 LO input - making for a 50 ohm termination).

  • Thanks for help.

    I don't understand this phrase very well : due to the small LO requirements of the LT5512. I didn't find any infomation about these requirements related in the datasheet...

    If I use HMC1033 in 50 ohm single-ended, what should I place for the unused port (for example OUT_N) ? Is a capacitor enough for this before connecting to ground ? Which value should I take ?

    I perfer using HMC1033 in differential mode to drive LTC5512 for improving CMRR purpose (LO input freq. about 200MHz). Do you have some suggestions for differential mode ?



  • LT5512 datasheet Page 2 has the LO input power specifications.

    For the unused port use a cap and 50ohm resistor as shown in Figure 20.  Refer to the eval board schematic for the value of the capacitor.

    You can use a differential signal just make sure you do not exceed the LT5512 page 2 LO input specifications.  

  • Thanks for explication.

    In datasheet of LT5512, page 8, I would like to know why the calculation of L1 and L2 doesn't take account the value 5.2 Ohm reactance (given by the input diff impedance). Or am I wrong ?

    Thanks in advances

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