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 Test Bench for Clocked Comparator 

Last post Mon, Jul 8 2013 3:55 AM by ksnf3000. 4 replies.
Started by ksnf3000 06 Jul 2013 06:06 AM. Topic has 4 replies and 1148 views
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  • Sat, Jul 6 2013 6:06 AM

    • ksnf3000
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    • Joined on Tue, Oct 30 2012
    • Posts 13
    • Points 200
    Test Bench for Clocked Comparator Reply
    Hi All,

    I have a clocked comparator. The differential stage in the design has a clock which allows it control the pMOS and nMOS transistors.

    The problem i am having is while doing the dc and ac simulations of the comparator. On giving a pulse input to the Vclk pin, i am not getting the desired result.

    Please let me know how the test bench should be for determining the dc and ac parameters of this circuit.

    Thanks,
    Kashif
    • Post Points: 20
  • Mon, Jul 8 2013 12:08 AM

    • VKhlyupin
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    Re: Test Bench for Clocked Comparator Reply

     What is your desired result?

    • Post Points: 20
  • Mon, Jul 8 2013 3:01 AM

    • ksnf3000
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    Re: Test Bench for Clocked Comparator Reply

     Hi,

     The desired result should be that of an ideal comparator.

     Regards,

     Kashif

    • Post Points: 20
  • Mon, Jul 8 2013 3:11 AM

    Re: Test Bench for Clocked Comparator Reply

    Kashif,

    Not sure your last response is terribly helpful (nor was the question from VKhlyupin to be honest).

    Anyway, you can only use ac analysis on a Linear Time Invariant system - but what you have here is a Linear Time Variant (or Linear Time Varying) system. Put another way, the ac analysis does a small signal analysis around a single dc point - but in this case your operating point is actually a period of the clock. So similarly dc doesn't make a whole lot of sense either.

    What you need to do is to use pss and pac to analysis your system. This allows you to look at the time-averaged AC response of the circuit over a period of operation. Whilst these analyses are commonly used in RF design, they are also suitable for other kinds of switching circuits such as switched capacitor filters, chopper-stabilized amplifiers, and switched comparators. See this paper for details on using it with switched capacitor design, for example.

    Kind Regards,

    Andrew.

    • Post Points: 20
  • Mon, Jul 8 2013 3:55 AM

    • ksnf3000
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    • Joined on Tue, Oct 30 2012
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    • Points 200
    Re: Test Bench for Clocked Comparator Reply

    Andrew,

    Thanks for your prompt response. The pdf is really helpful as I am working on switched capacitors which uses a clocked comparator.

    Regards,

    Kashif

    • Post Points: 5
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Started by ksnf3000 at 06 Jul 2013 06:06 AM. Topic has 4 replies.