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 Charge Pump output Capacitance 

Last post Mon, Jul 8 2013 6:40 AM by Andrew Beckett. 8 replies.
Started by Mushir 08 Jul 2013 03:46 AM. Topic has 8 replies and 913 views
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  • Mon, Jul 8 2013 3:46 AM

    • Mushir
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    • Joined on Mon, Jul 8 2013
    • Posts 5
    • Points 85
    Charge Pump output Capacitance Reply

    Hi 

     I am using a capacitive load in charge pump in CADENCE h035 technology. But when I am creating charge pump symbol and using it in other circuit   its showing errors while simulating (runs upto 1% and the spectre error) I know its due to the load at the output port of Charge pump but I dont know how to use it or replace it because that output capacitance is very important.

     Please suggest me something.

     Thanks in advance.

     

    Mushir 

    • Post Points: 20
  • Mon, Jul 8 2013 3:57 AM

    Re: Charge Pump output Capacitance Reply

    Mushir,

    I would respectfully ask you to read the forum guidelines. A few points:

    1. There is no such thing as "CADENCE h035" technology. Cadence provides the EDA tools, but does not provide manufacturing technology - so you're presumably talking about a Process Design Kit from some foundry or other - knowing which one would likely help anyone answering your question.
    2. You didn't say what the actual problem or error was
    3. You didn't say what tool versions you're using
    4. Showing your circuit would most likely help.

    But this kind of thing is all in the guidelines.

    Kindest Regards,

    Andrew.

    • Post Points: 20
  • Mon, Jul 8 2013 4:57 AM

    • Mushir
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    • Joined on Mon, Jul 8 2013
    • Posts 5
    • Points 85
    Re: Charge Pump output Capacitance Reply
    Hi Andrew

    Yeah I did a mistake while writing the technology and tools. I am using AMSh0.35um technology and Virtuosos 6.1.5 tool.  The actual problem is that when I am using the Symbol of this charge pump circuit with the output capacitor load and then integrating it with other circuit(basically a switch in this case) there is Spectre error coming. If I am using it without the load capacitance then its working fine. But I need the load capacitance in the charge pump.

    I have attached the circuit below.

    Thanks

    Mushir
    • Post Points: 20
  • Mon, Jul 8 2013 5:35 AM

    Re: Charge Pump output Capacitance Reply

    Hi Mushir,

    No circuit was attached, and you didn't show the error...

    Kind Regards,

    Andrew.

    • Post Points: 20
  • Mon, Jul 8 2013 5:38 AM

    • Mushir
    • Not Ranked
    • Joined on Mon, Jul 8 2013
    • Posts 5
    • Points 85
    Re: Charge Pump output Capacitance Reply

    Hi Andrew

     

    I pasted the circuit schematic but I dont have any idea why its not showing in the post. It went through some moderation also before getting posted. I am new to this forum so I am not sure what is the problem with it.

     

    Thanks

    Mushir 

    • Post Points: 20
  • Mon, Jul 8 2013 5:47 AM

    Re: Charge Pump output Capacitance Reply

    Mushir,

    Use the Options tab at the top of the page to attach a picture (e.g. a png file) rather than trying to paste in an image.

    Regards,

    Andrew.

    • Post Points: 35
  • Mon, Jul 8 2013 6:16 AM

    • Mushir
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    • Joined on Mon, Jul 8 2013
    • Posts 5
    • Points 85
    Re: Charge Pump output Capacitance Reply

    Hi Andrew

     I have attached the screenshot of the circuit scematic and error screen.

     

    Regards

    Mushir


    • Post Points: 5
  • Mon, Jul 8 2013 6:18 AM

    • Mushir
    • Not Ranked
    • Joined on Mon, Jul 8 2013
    • Posts 5
    • Points 85
    Re: Charge Pump output Capacitance Reply

     Hi Andrew

     This is the error screen

     Thanks

    Mushir


    • Post Points: 20
  • Mon, Jul 8 2013 6:40 AM

    Re: Charge Pump output Capacitance Reply

    It's still not really enough to go on. Presumably the convergence difficulty is caused by some numerical instability in the circuit - and without seeing the data, it's going to be very hard to debug (you didn't mention which device makes the difference). Usually small timesteps are caused by discontinuities in the device models, combined with large component values (or negative component values). I see you have a 500pF cap there, which is large (for IC) but not immense. There appear to be some 50uF capacitors too - but maybe that's just the resolution of the image - driving these with a 10u/0.5u transistor seems a bit hopeful.

    Maybe you should contact customer support? Then we can properly look at your data, maybe.

    Regards,

    Andrew.

    • Post Points: 5
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Started by Mushir at 08 Jul 2013 03:46 AM. Topic has 8 replies.