Analog Phase Shifter control voltage? HMC-C010 and HMC247

Hello,

I'm a little confused about the description in the datesheet. It says the the phase is "controlled via an analog control voltage ". However, the provided data sheet gives the performance at with DC control voltages only. The control pins seems to be designed to a DC voltage as well.


Would this "50MHz modulation bandwidth" allow to control the phase by a 10MHz sinusoid for example?

Are there any S11 v.s. Vctl  measurements available?


Thank you.

  • 0
    •  Analog Employees 
    on Feb 23, 2016 10:46 PM

    Hello,

    Yes, the phase can be controlled using a 10 MHz sinusoidal input to the Vctl pad.

    During our product validation the modulation bandwidth was measured as follows:

    RFIN = -10 dBm @ 6 GHz

    Vctl Pin = -20 dBm @ 10 MHz (Vctl modulates the RFIN signal, producing sideband signals 10 MHz away from 6 GHz)

    At RFOUT a sideband signal was measured as the reference amplitude.

    The frequency of the Vctl signal was then increased until the sideband signal had dropped by 6 dB (relative to the reference amplitude).

    The frequency at which the 6 dB drop was observed is the modulation bandwidth.

    The procedure above was then repeated for RFIN at 11 GHz and 15 GHz.

    We do have S11 vs. Vctl data.

    Please see the attached tab-delimited text file containing data from one of our product validation devices.

    Regards,

    SMcBride

    HMC247_SN1_25C_SP_vs_Vctl.txt.zip
  • Dear SMcBride,

    Thank you for your reply. It was really helpful. It turns out that a BNC cable wasn't soldered properly to the Vctl pin, and that gave inconsistent results. After fixing the issue I was able to see the sidebands, and indeed they're 6dB lower at 50 MHz compared to 10 MHz.

    In addition, what I originally meant by S11 vs. Vctl is the actual reflections at the Vctl pin. I did measure it and it turns out that the reflections @ 10MHz ((-0.46dB)) are much more than the reflection @ 50 MHz Vctl ((-5.3 dB)). While this might not very  important in practice, I beleive for characterizing the device or determining a modulation index, these reflections should be taken into account. Since now the the power actually going into the device's control pin at 50 MHz is actually multilple times larger than the power at 10 MHz even though the external supply's power is fixed.

    Furthermore, are there any maximum "Rf" Vctl power ratings that you may suggest ?

    Thank you.

    Regards

    Mohammed

  • 0
    •  Analog Employees 
    on Mar 1, 2016 12:48 AM

    Hi Mohammed,

    The HMC247MS8G is an old part for which we do not have Vctl pin S-parameter data.

    Also, I was not able to find info regarding a max RF Pin to the Vctl pin.


    When you were driving the Vctl pin with RF, was the modulating signal input directly to the Vctl pin, or was some type of DC bias applied to the pin (e.g., to bring it to 5 V...the midpoint of its 0 V - 10 V operating range) while the modulating signal was AC-coupled to the pin?

    Regards,

    Sean

  • Hi sean

    No I don't recall adding any DC offset, do you think that may reduce reflections?

    I was using the HMC c010 by the way.

    Regards,

    Mohammed

  • 0
    •  Analog Employees 
    on Mar 1, 2016 11:53 PM

    Hi Mohammed,

    Did you have any questions about the HMC247MS8G in particular?

    I ask because I support that product, but a different applications engineer supports the HMC-C010.

    I've notified the HMC-C010 supporting apps engineer of this thread, so he will likely comment soon.

    Regards,

    SMcBride