13.56Mhz Class E Power Amplifier for Plasma Generation

Discussion in 'Homework Help' started by keathow87, Feb 6, 2011.

  1. keathow87

    Thread Starter New Member

    Feb 6, 2011
    9
    0
    hi, friends...I'm currently working on my Final Year Project to construct a plasma needle and facing problems in construct my RF supply. I'm using MOSFET IRF540N in my circuit as switching device and got some question here:

    1) Does this IRF540N actually require Vgs of 15V to on/off it instead of the 2.5V shown in the datasheet?

    2) The current instrument available for me only manage to provide a 13.56Mhz, Vpp of 2.5V square wave to my MOSFET, and it is a function generator. Is it possible for me to amplify the signal to Vpp of 15V?? what circuit needed to do it??

    3) Any gate drive circuit available to provide a Vpp 15V, 13.56Mhz square wave if it is impossible to amplify the signal from function generator?

    I'm really in need of your kind help and run out of time, so please help me:(
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,671
    897
    Neither. Vgs of 15 V is not needed to turn it off. Vgs of 10V is needed to turn it on fully. The datasheet is correct. You apparently don't understand what V threshold means.

    Yes. You had better check the switching times for that mosfet. It may not operate too well at that frequency. Here is a discussion on design of high-speed drives and limitations: http://focus.ti.com/lit/ml/slup169/slup169.pdf

    Yes. Although, most gate drivers do not generate the actual driving frequency. They simply produce the current and voltage needed. Some drivers are designed to produce both top and bottom drive signals for an H-bridge from a single input.

    When is it due?

    John
     
    Last edited: Feb 6, 2011
  3. keathow87

    Thread Starter New Member

    Feb 6, 2011
    9
    0
    jpanhalt, thank you so much for the reply...I'm sorry for din't notice it since no email was send to notify me:D

    http://images.elektroda.net/28_1297149430.jpg
    this is the ideal output i want to get, the MOSFET available in this simulation is IRF530N. However, the input from XFG1 is only a 13.56Mhz, 2.5Vp square wave and it works perfectly well. Why it comes to a problem when test in real practice?


    http://images.elektroda.net/42_1297149430.jpg
    btw, i tried to amplify the voltage from the output of function generator and that's what i get. I was manage to amplify it from Vp of 2.5V to 10V now but it's still useless when come to connect the C2 to the gate of MOSFET. Can any1 tell me why it failed??

    http://iopscience.iop.org/1367-2630/6/1/149 is what I was trying to achieve but my deadline is end of March. Right now I'm just looking for any circuit that can help me to produce the plasma, I mean I'll be really satisfied as long as i can see the purple glow on the needle neglecting its characteristic:(
     
  4. keathow87

    Thread Starter New Member

    Feb 6, 2011
    9
    0
    Alright, I'm not sure is it a good news or bad news. My instructor finally agreed to buy some component for my project, but the budget can not be too high. 2 things i need now are IXYS RF-DEIC420-IC,DRIVER,MOSFET DE275 and IXYS RF DE275-501N16A, if I can only choose one, which one is most needed in my project?

    1) Is it possible to generate the plasma by using the DEIC420 to drive the IRF540N MOSFET? i heard that a RF MOSFET like DE275 series is more suitable in generating plasma but the problem is out of budget. The MOSFET is even expensive than the MOSFET driver...any suggestion please?? thank you...
     
  5. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,671
    897
    A couple of observations. The simulation for your driver shows the effects of capacitance and resistance. Essentially, your output at 13 MHz is at 500 Ω into 0.1 uF. That is a lot.

    As for driving that mosfet at 13 MHz, you should review how gate drivers work. Here is a relevant excerpt from good review:

    Second, it would be helpful if you could give more detail about what you have done and what you mean by it "not working."

    Finally, please post your images on the local server. Going off site can create unnecessary delays and other problems.

    John
     
    keathow87 likes this.
  6. keathow87

    Thread Starter New Member

    Feb 6, 2011
    9
    0
    John, can you please show me any circuit can be use to ON/OFF a MOSFET?? I got no idea how to do it even after read many articles/datasheet @.@

    All i got is a function generator can output a 2.5Vp square wave and its obviously not enough to turn On the MOSFET as other people do...I know that a oscillating Vgs =10V and -10V needed to do it but i just don't know how....please help me...
     
Loading...