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plot graph for quality factor and capacitance vs frequency

manjeet0000

 Hello

I am working on LC VCO.I am using cadence 0.18 um and  I tried to simulate the vermis_18f component (varactor) in 0.18 um in cadence spectre. i have done connections using port 1 connected to one side (assuming it as gate) and port to the other pin of the component with body also shorted to this pin ( i suppose that body=source= drain are connected). am i correctly doing this?

i was able to plot waveforms for Z11 parameter real part and imaginary part.

1) As Q= Im(Z)/Re(Z)  ,but i am not able to plot it as waveform using calculator.Please help me regading this

2) Also how to plot c-vgs curve in spectre??

Thanks in advance

manjeet






thanks
manjeet 

  • ninjaa

     Hi,

       There how you can do it simply

    1 ) Connect a port to varacter and set DC voltage inside the port to Vdd

    2) Run sp analysis with Vdd set to some value

    3)The imag(Y11)/2*pi*f is your varacter capacitance at that paricular Vdd and frequency

    4) Now sweep Vdd

    5) Go to calculator get the expression like  (value(imag(yp(1 1 ?result "sp")) 1e+09) / (2 * 3.1415 * 1e+09)) . You can use your own desired frequency.

    6)Press plot button

    7) For diode or MOS varacter  you get its characteristic CV curve curve

     

     

    Verification:

      Connect an ideal cap of 1 pF and repeat the same for comparison but offcourse without Vdd.

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