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29th May 2006, 04:44 PM  #11  
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Quote:
______________ Prasanna Rao. 

30th May 2006, 12:03 AM  #12 
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In order to obtain a high Q, your source impedance needs to be as high as possible. Maybe you could try using a voltage source instead of the current source and using a large value of discreet resistance in series with this. At least then you would have this control.

31st May 2006, 12:13 PM  #13 
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The formula for the resonant Q of that parallel RLC circuit is given by Q=R*sqrt(C/L). The Q changes when you change the ratio of C and L.
Regards, Ray 
1st June 2006, 01:38 PM  #14 
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you might need to dig into spice settings that control the accuracy and defaults of the simulation, in LtSpice a default R damps inductors without explicit Rser declarations, you have to turn it off in the control panel
in .ac sim you need to use a very fine frequency grid to hit the 1/(2*pi) * 10e6 resonance exactly, or change component values to match a even frequency with LtSpice I get ~ 1% amplitude difference even with 10000 points/oct freq resolution 
1st June 2006, 04:43 PM  #15 
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2nd June 2006, 07:44 AM  #16  
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Quote:
That's right. But i havent found any data in the model of L in PSPICE; which represents its series DC resistance. Surely, Rseries is the only reason for the nonideal voltage response in my experiment. I am trying to go deep into PSPICE and seek that Rseries data for L. If anyone knows regarding it then kindly present them in this thread. Regards Prasanna. _______________ 

2nd June 2006, 11:37 AM  #17 
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Now problem in Transient Analysis
Oh great..! The problem for AC sweep is solved. I increased the points/octave value to 10000 and the response is almost perfect.
But the transient reponse is absurd. Its showing amplitude of Vr = 10V at resonance, where should actually be 100V. Whats this problem for..? I have attached the transient response with this post. Kindly reply if anyone has any answer. _________________ Regards Prasanna. 
2nd June 2006, 11:42 AM  #18 
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Just a thought, your time stepping seems a little coarse.

2nd June 2006, 11:45 AM  #19  
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Quote:
Didnt get it.. .. Could you pls elaborate more on that.. Regds Prasanna _________ 

2nd June 2006, 12:19 PM  #20 
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As spice samples in transient mode, it takes samples at intervals of time. These intervals are referred to as the time step. Your plot looks a little low res (pointy )

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