Muting RF output in ADF4360-1

I need disable/enable RF output of ADF4360-1 quickly, i.e. in less than 1 microsecond.

There is no single pin like "TXON" or "Output Enable". I don't see a way to access "MUTE" block either, which is driven by "Lock Detect" only (?).

My question is:

May I disable RF output by disconnecting RFoutA and RFoutB pins from DC supply?

In that case, all the tail current of the output differential pair transistors would flow probably through their B-E junctions; is it safe?

Any other suggestions how to mute RF output quickly?

Thanks in advance

  • 0
    •  Analog Employees 
    on Oct 19, 2011 4:45 PM over 9 years ago

    Hello  ,

    Yes it is possible to disable the RFOUT by removing the power to the RFOUT pins, and this can be implemented using a standard transistor and a pulse generator, however, after it is re-applied the output frequency can show a pulling effect, and will need to re-lock.

    The CE pin is generally used to control RFOUT on/off time, but again, the device will need to re-lock.

    Regards,

    Brigid.

  • Hi Brigid,

    I understand from your post that switching DC supply to RFOUT pins OFF and ON shall not impair the ADF4360 chip, but PLL lock may be temporarily lost due to VCO frequency pulling. Hopefully, the pulling will be not that strong when using the freq/2 option, and possible re-lock, if it still occurs, shall be very quick ;). Anyway, I must check it experimentally.

    In my design, I did not even think about using CE pin to control RF OUT, because I have no time to wait for PLL to lock - the synthesizer must be locked on a specified frequency to be ready for immediate use when needed, and otherwise stay quiet - no interferences for receiver located on the same PCB.

    The solution with switching DC supply to RFOUT pins seems to me quite interesting, as it keeps all RF oscillations within IC, and possibility of leakages to next circuits is minimized.

    By the way, it would be nice if ADF4360xx had a separate pin to control MUTE circuit directly (now driven by LOCK DETECT only)...

    Thanks,

    Andy

  • 0
    •  Analog Employees 
    on Nov 30, 2011 6:02 PM over 9 years ago

    The ADF4350 has a mute function which may be more suitable for your application.