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According to some reference books,impedance can be calculated by the following equations.
Z1 = (1+S11)*Z0/(1-S11)
Z2 = 2Z0*(1/S21-1)
where,S11 and S21 are Sparameters and Z0 is the characteristic impedance (50Ohm).
I simulate a resonator and plot Z1,Z2,but Z2 seems to be strange.
(There...
FvM, thank you so much.
So far, overtone oscillation does not occur.
Sorry,I mistook my question..
What I wanna ask is not the role of C2 but the role of C1.
It seems to be irrelevant to positive feedback.
Hi there,
I'm trying to design a crystal oscillator by refering the document.
**broken link removed**
(Please see "9.0 Typical Applications" 100kHz crystal oscillator)
However,I can't understand the oscillation mechanism.
How does the oscillator work??
I think 100kHz crystal and 10pF makes...
I'm trying to simulate the loaded Q of Xtal oscillator to estimate the phase noise by using Lesson's formula.
How can I calculate the loaded Q?
Do you have any reference about it??
I believed parasitic oscillation was derived from an unwanted feedback path..
I can't understand the words "different modes the crystal can operate".
The two oscillations are compatible??
explanation of a resistance equation
Thank you for the detailed comment!
I didn't know an oscillator can be defined as 2 different viewpoints.
I simulated the negative resistance of some oscillators,
and the results showed the negative resistance was proportional to C2/C1.
So,I doubted the...
colpitts negative resistance
>Zin= 1/sC1 + 1/sC2 - gm/(ω^2C1C2) Is that what you mean?
>Maybe C1/C2 affects the bias point of the transistor?
No,I'm focusing on the real part.
As you said,C1/C2 may change the transistor condition..
I might mistake the premise.
Maybe I ought to consider the...
math equation negative 35
Yes,I agree with you.The equation itself is correct.
But I think it is not perfect.
I believe there is more accurate expression to describe the negative resistance.
For example,
R = -gm/(ω^2C1C2) + f(C1,C2,C1/C2)
Of cource,the dimension of the additional term is ohm.
Re: Input impedance
Z0 is the characteristic impedance of feed line.
You can use the equation for any 2-port passive circuit because the reflection coefficients are directly linked the impedance.
If you want to know the detail of the circuit,you assume the equivalent circuit and optimize it...
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