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MOSFET I-V characteristics using Probe station and Agilent's parameter Analyzer

Discussion in 'General Electronics Discussion' started by nikhil678, Jun 10, 2013.

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  1. nikhil678

    nikhil678

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    Jun 10, 2013
    Hey guys,

    I am using a CD4007 UB chip to analyze the IV characteristics of a PMOS and NMOS individually. The parameter analyzer allows me to provide voltages only at the gate, source and drain. For NMOS, I gave 0V to source (pin 7), 0 to 5V swing to gate (pin 6) and 0 to 5V swing to drain (pin 8).

    For PMOS, I gave -5 to 0V to the gate(pin 6), 0v to source (pin 14) and -5 to 0V to the drain. (pin 13). I an not able to receive the desired waveform with these readings. Am I doing anything wrong?

    Please let me know.

    Thanks,
    Nik
     
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Thanks for the thorough description of the problem.

    That's an interesting project.

    My guess is you may be getting interference from the N-channel MOSFET. The 4007UB gate contains both the P-channel MOSFET (source connected to pin 14) and the N-channel MOSFET (source connected to pin 7) and it's impossible to separate them.

    To minimise interference from the other MOSFET, I would connect the other MOSFET's source pin to the drain of the MOSFET being measured. For example, when testing the P-channel MOSFET, connect pin 7 of the device to the drain (pin 8). Do not apply a voltage between pins 7 and 14 (as you would normally do in a practical application of the 4007UB).

    You may also want to connect the inputs of the unused gates to the input of the gate you are measuring.

    Good luck and please keep us posted on your results.
     
  3. nikhil678

    nikhil678

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    Jun 10, 2013
    Hi Kris,

    Thank you so much for your response.

    The problem is that I am using a probe station and it has only 4 probes. So if 3 probes go on the gate, source and drain of the NMOS, and if I place the fourth probe on source of the PMOS (pin 7), I am not sure how I can physically connect the 2 source.

    Also, since not more than 4 probes are available, I cannot connect the unused gates to the input of the gate i am measuring.

    I did get the correct waveform for the NMOS by just connecting probes to the gate, source and drain. However for the PMOS although it starts alright, after Vd goes above 1V, the waveforms go haywire.

    I am still trying to figure out how I can get the correct waveform.

    Thanks Again for the help. Please let me know if you know of any other alternatives.
     
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Can't you connect the appropriate pins together before you connect the probes?
     
  5. nikhil678

    nikhil678

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    Jun 10, 2013
    I am using a CD4007 dye which is less than 1mm x 1mm. I am not sure if there is a way to connect 2 pins of the chip. Do you have any suggestions how I can do that?
     
  6. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Oh, you're probing a silicon die directly? No, I don't have any suggestions; that's way outside my experience, sorry.

    If you're just interested in the I-V characteristics of N-channel and P-channel MOSFETs, why can't you use actual N-channel and P-channel MOSFETs instead of a CD4007UB?
     
  7. nikhil678

    nikhil678

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    Jun 10, 2013
    My project is to verify MOSFET characteristics using CD4007. I need to check if it works, so that if it does, we can use it for further applications. Is there a way to upload a picture here? I can show you the waveform I have received and the values I put in for it.
     
  8. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Yes. Click the "Go Advanced" button, and find the Attachments button (top line of the toolbar above the edit window, about 2/3 of the way along). This brings up the Attachments dialog. You can browse for files, then click the Upload button. File size limits are listed. This will show them as thumbnails.

    You can also put images inline in your post if you right-click the uploaded file name on the attachments dialog and choose Copy URL (or similar), close the dialog, and insert an image (bottom line of the toolbar) and paste the URL.

    If your image is a diagram, rather than a photo, it may be best to upload it as a GIF or PNG file. You may be able to reduce the number of colours to, for example, 16 to reduce the file size, if it's too large to attach.
     
  9. nikhil678

    nikhil678

    12
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    Jun 10, 2013
    PMOS waveform

    Hi Kris,

    This is the waveform that I received for PMOS.
     

    Attached Files:

  10. nikhil678

    nikhil678

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    Jun 10, 2013
    Is it visible Kris?
     
  11. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Yes I see the diagram, but I'm not sure what I'm looking at!

    Why are there so many traces on the graph? What is the significance of each one? Are they different gate voltages? If so, can you mark the voltages next to the traces?

    Could you upload the traces you got for the N-channel MOSFET for comparison?

    I must warn you, I may not be able to help. I've never used the kind of curve tracing equipment you're talking about.
     
  12. nikhil678

    nikhil678

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    Jun 10, 2013
    Hi Kris,

    I am sorry for not responding so long. For Vds of 0V to 5V, Vgs 0 to 5V, for NMOS i got the following graph. The values go unto 5 mA. is this correct? shouldn't it be in Micro Amps? Is there a way to confirm if the readings I am getting is correct?
     
  13. nikhil678

    nikhil678

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    Jun 10, 2013
    Here it is
     

    Attached Files:

  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    That looks right.

    I suspect your 4 lines are at different gate voltages

    Given they're normal CMOS devices, milliamps sounds right.
     
  15. nikhil678

    nikhil678

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    Jun 10, 2013
    Hi Steve,

    Thanks for your prompt response. I am using the probe station and parameter analyzer with a CD4007 for this project. I have received the graph for NMOS. But for PMOS i am getting a funny graph as follows.

    Also, is there a way to verify what values am I supposed to get. Like a data sheet or paper or something?
     

    Attached Files:

  16. nikhil678

    nikhil678

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    Jun 10, 2013
    I need to have a precise document, which proves that the results I am getting are correct.
     
  17. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    I doubt you can prove the results you get are correct. In any case, they will always be subject to experimental error and variation between parts.

    If the 4007 documentation doesn't describe the devices, maybe an old application note might. I would tend to look for an old NS (National Semiconductor) document as I had good experiences with them 20 (or was that 30) years ago...
     
  18. nikhil678

    nikhil678

    12
    0
    Jun 10, 2013
    Hi Steve,

    Thanks. I will look into it. Also, this question is really funny and I apologize in advance if it is too trivial to answer, but is there a way I can plot the MOSFET voltage characteristic graph using Microsoft Excel? I have the values for Id, Vd and Vgs. I have tried many things but I can't plot it. Is there a way to plot in on excel. Please let me know.

    Thanks Again for all the help.
     
  19. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Well, excel has a significant number of graphing options. I use it all the time for presentation of data in graphical form.

    I'm sure you could make something work.

    For what you're doing here, I find one of the variants of X-Y graphs work best.
     
  20. nikhil678

    nikhil678

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    0
    Jun 10, 2013
    How can I plot Vgs, with values of 0 to 5V, as a function of both Vds and Id on Excel. I am not able to figure out how I can do that. I tried all doing my best with it, but no luck.

    Do you have any suggestions?
     
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