RF/voltage clamp/limiter

Discussion in 'Wireless & RF Design' started by Tako, Jul 19, 2016.

  1. Tako

    Thread Starter New Member

    Oct 21, 2014
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    Hi,

    I'm looking for a circuit that is called "RF clamp", "RF limiter", "voltage clamp" or "voltage limiter".
    The example of such circuit is a transistor Q on this picture:

    http://i.stack.imgur.com/j8EGx.jpg

    However, what I need is a full RF clamp circuit. Not only the transistor shown in the example above. The gate bias of this transistor would be very useful.

    I cannot find many of such circuits. Often, they are stacked diodes on antenna lines or diodes + resistor to bias transistor clamp.

    Do you know where I could find good examples? Any books, websites?
     
  2. BR-549

    Well-Known Member

    Sep 22, 2013
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    It would be hard to say. Not quite sure what you mean. The Q in your example is not a clamp, it's a switch.
    And not sure what is meant by full rf clamp, unless you mean grounding or disconnecting the antenna.
     
    Last edited: Jul 20, 2016
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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  4. Tako

    Thread Starter New Member

    Oct 21, 2014
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    @BR-549
    Could you please, say what you do not understand, so I could explain a bit more?

    Maybe this picture would be better: https://www.google.pl/imgres?imgurl=x-raw-image:///f4c1e3144cdc3e98e4363d638d6c17d10b2a5f2caf9eccef62d63f8037c7ba39&imgrefurl=http://75.127.14.226/downloads/ims/arftg_imsproceedings/ims_proceedings/PDF/124:shock:L7DaCQtLrCf-2.pdf&docid=ck0fkoNyabWGGM&tbnid=mD7cTBTjwfSQZM:&w=526&h=296&bih=799&biw=1440&ved=0ahUKEwiB_-zH9P_NAhXCd5oKHQONBbkQMwgiKAQwBA&iact=mrc&uact=8

    I need a schematic of RF clamp circuit to be implemented in CMOS IC process.


    @Kermit2
    I do not need separate element or IC XD.
    I must implement such RF clamp in my CMOS IC process.
     
  5. BR-549

    Well-Known Member

    Sep 22, 2013
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    Have you got the data sheet on your CMOS IC chip?
     
  6. Tako

    Thread Starter New Member

    Oct 21, 2014
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    What exactly do you mean? Any specific parameter? I need to clamp antenna lines so that there would be no more than 3.6 V.
     
  7. BR-549

    Well-Known Member

    Sep 22, 2013
    2,004
    394
    Are you working with a already manufactured chip, or are you designing a new chip?

    Do you know what a data sheet is? What is a CMOS IC process?

    And, the part of the circuit that you want to limit, is that part of the circuit, used for transmission also?

    We can't offer solutions, without understanding what you are doing. All the little details, makes ALL the difference.

    So, how do you want to proceed?
     
  8. Tako

    Thread Starter New Member

    Oct 21, 2014
    23
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    I see. I was not aware that I was not clear in my description.

    Details are as follows:

    1. I'm designing a new chip.

    2. CMOS IC process: 0.18 um 3.3 / 1.8 V.

    3. Yes, the clamp should be on antenna lines that are both used to receive power from RF 13.56 MHz field and to transmit data.
     
  9. BR-549

    Well-Known Member

    Sep 22, 2013
    2,004
    394
    Tako, I was suspecting that. Sorry my friend, 0.18 um is out of my league. The closest I get to a chip is the datasheet.

    I believe there are members on here that design chips, but have not seen it discussed.

    Good luck on your quest.
     
  10. Tako

    Thread Starter New Member

    Oct 21, 2014
    23
    0
    Thank you BR-549 just for being interested into helping me :) !
     
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