Queries about HMC284AMS8G Crosstalk

hi, all     We use HITTITE's HMC284AMS8G some questions, please help deal with that when HMC284 for low frequency (1Mhz below) there was a clear Cross Talk, but we've no problem with the HMC252, please help analyze how to deal with this case        Details are as follows, When RFC 100K input signal, output is set to RFC to RF1, RF2 theoretically there should be no output at this time, but actually seeing the obvious CrossTalk on RF2 thanks! Br, Wayne

  • Hi Wayne,

    HMC284AMS8G's  s-parameters was evaluated down to 10MHz so we don't have isolation measurement data at 100kHz. What is the frequency range of your application? Did you repeat your measurement at higher frequencies like 100 MHz in your test setup (signal generator and oscilloscope should be 50 Ohm equipment and unused port RF of the HMC284AMS8G's should be terminated to 50 Ohm) and replicate the datasheet results (~50 dB isolation)?

    Do you use HMC284AMS8G Eval Board for your measurements? The external DC blocking capacitors of 100pF used at RF ports of HMC284AMS8G Eval Board might have big insertion loss and degrade the part performance at 100kHz. 0.1uF to 1uF would be used as DC blocking capacitors at 100kHz. I understand from your measurement results (insertion loss from RFC to RF1) that you have used bigger external DC blocking capacitors to operate the part at 100KHz. Can you tell me the value  the value of DC blocking capacitors you used?

    BTW, negative voltage controlled switches would be a better solution to work at 100kHz since they do not require DC blocking capacitors at RF lines.

    Regards,

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    •  Analog Employees 
    on Aug 2, 2018 2:51 PM
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