VCO tuning range plotting

• Sep 28, 2006

• #1

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ravet

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Hello

how can i simulate the tuning range of the vco, frequency vs control voltage , using cadence spectre??

 

• Sep 28, 2006

• #2

aomeen

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Re: coil and varactor simulation

To simulate Inductor you need use S-Param simulation... You can find expressions for L and Q in terms of S11,S12,etc. Similarly you can make sweep on voltage applied to a varactor, and plot imag(Y11), which is the capacitance...

 

• Oct 6, 2006

• #3

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Grig

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Re: coil and varactor simulation

You need simulate Y(1,2) for series inductor or varactor
if varactor shunt then you need Y(1,1)

for inductor L=imag(-1/Y(1,2))/2/pi/freq (Henry) Q=imag(-Y(1,2))/real(Y(1,2))
for var C=imag(-Y(1,2))/2/pi/freq Q=imag(Y(1,2))/real(Y(1,2))

 

• Oct 12, 2006

• #4

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sengyee88

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Try this
h**p://

 

• Oct 12, 2006

• #5

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sarath451

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You need simulate Y(1,2) for series inductor or varactor ,if varactor shunt then you need Y(1,1),for inductor L=imag(-1/Y(1,2))/2/pi/freq (Henry) Q=imag(-Y(1,2))/real(Y(1,2)) ,for var C=imag(-Y(1,2))/2/pi/freq Q=imag(Y(1,2))/real(Y(1,2))

 

• Oct 13, 2006

• #6

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lijianheng

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You can use the PSS analysis, enable the sweep button and choose the parameter of voltage.
See the result in harmonic, then you can see the curve.

 

• Oct 14, 2006

• #7

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tsinghua

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PSS is very slow, if there are a lot of sweep points.
I like to invoke the sweep tool, run tran simulations and extract a frequency estimation by using freq function.

 

• Oct 17, 2006

• #8

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shaikhsarfraz

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Hi,
For plotting VCO tuning curve

perform PSS analysis with sweeping Vcontrol as the the parametric variable.

thanks
sarfraz

 

• Oct 17, 2006

• #9

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czn

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1.set the parametric variable (control voltage ex:Vt)
2.sweep the Vt with "transient analysis"
3.plot "output"

 

• Oct 18, 2006

• #10

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nickoo

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Simple eg:
.tran 0.1p 100n Sweep Vctrl 0.7 2.7 0.1
~~~
.meas FreqVcoout

open awaves to view FreqVco~Vctrl

it work well

GOOD LUCK

 

• Jan 4, 2007

• #11

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liangshangquan

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set a variable to a node ,sweep the trans

 

• Nov 4, 2010

• #12

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lisamoni

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hi nickoo,
i didnt understand the syntax.i couldnt run it,error occurs.my output node is ck1.than what will be the syntax?please tell me,please

 

• Nov 4, 2010

• #13

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dick_freebird

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You might find it better to use parametric analysis, with a
transient simulation lasting some number of cycles and the
frequency calculated from the last two zero-crossings. A
sweep with Vtune moving quickly relative to cycle frequency
may be inaccurate at any given Vtune point, and a slow
Vtune with a lot ov cycles is an unberable solution time.
You probably do not need great Vtune granularity for most
uses, and certainly not "continuous" variation.