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Hysteresis sweep option in DC

sohaiba

Hi,

I haven't been able to see a Hysteresis plot by using the DC Hysteresis sweep option. I have also enabled the 'DC operating point' option as well. I was expecting to find a negative going plot as well for the device but there is only a single Voltage transfer characteristic curve.

 Following are the settings the Cadence spectre.out shows.

Important parameter values:
    reltol = 1e-03
    abstol(V) = 1 uV
    abstol(I) = 1 pA
    temp = 120 C
    tnom = 27 C
    tempeffects = all
    gmindc = 1 pS
    hysteresis = on

Which verifies that hysteresis option is "ON".  I am using MMSIM 11.1 and Cadence 6.1.5. Could you indicate where I could be going wrong?

Regards

 

 

Parents
  • Andrew Beckett

    The "size of the eye" was a throwaway comment because the graph is somewhat like an eye diagram (not really because that's usually for clocked systems where you have jitter causing the position of edges to move back and forth). With eye diagrams you have the idea of an eye width - but that's not how you'd measure it here.

    You can measure the width of the opening - which corresponds to the hysteresis - by doing something like:

    cross(v("/VOUT" ?result "dc") 0.6 1 "rising" nil nil  )-cross(v("/VOUT" ?result "dc") 0.6 1 "falling" nil nil  )

    Note that the resolution will be limited to the step size you use in the dc sweep.

    Regards,

    Andrew.

Reply
  • Andrew Beckett

    The "size of the eye" was a throwaway comment because the graph is somewhat like an eye diagram (not really because that's usually for clocked systems where you have jitter causing the position of edges to move back and forth). With eye diagrams you have the idea of an eye width - but that's not how you'd measure it here.

    You can measure the width of the opening - which corresponds to the hysteresis - by doing something like:

    cross(v("/VOUT" ?result "dc") 0.6 1 "rising" nil nil  )-cross(v("/VOUT" ?result "dc") 0.6 1 "falling" nil nil  )

    Note that the resolution will be limited to the step size you use in the dc sweep.

    Regards,

    Andrew.

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