15 Threads found on edaboard.com: Barkhausen Criterion
There are always lots of different definitions for phase margin.... it becomes sometimes quite confusiong.
The phase margin problem hapens when you have a feedback system.
I believe that the best definition is:
1- A feedback system becomes unstable if the total phase delay of the system is greater than or equal to 360 degrees (Bar
Analog Circuit Design :: 09.10.2004 11:18 :: sinatra :: Replies: 7 :: Views: 2804
a phase shift oscillator is just basically a type of oscillator. a phase shift oscillator is a feedback oscillator. for a feedback circuit to be an oscillator it must satisfy two conditions (known as the barkhausen criterion). one is that the gain around the closed loop should be unity. and the phase shift around the closed loop should be zero.
Electronic Elementary Questions :: 08.01.2005 13:40 :: samcheetah :: Replies: 2 :: Views: 2416
When I design a ring osc VCO, I run into a problem when I want to simulate the delay cell's gain. I used a pseudo-differential delay element(Sungkyung Park et al.,Elec. Letters May,2001)
My question is: how to consider (both in theory and in simulation) the pseudo differential delay element?s gain? According to the barkhausen Cr
Analog Circuit Design :: 23.08.2006 01:56 :: trashbox :: Replies: 2 :: Views: 1104
Hartley Oscillator - b/c of it's Inductive divider....split inductance.
The frequency of oscillator should be:
f = 1/(2*pi*√(L*C))
if you NEGLECT the transistor capacitances.
Otherwise, you have to replace the transistor with its small signal model and calculate the loop gain. Finally, apply the barkhausen criterion to obtain an
Analog Circuit Design :: 05.05.2007 00:16 :: zeeshanzia84 :: Replies: 5 :: Views: 765
you need to give an initial condition to start the oscillator, is it a 5 stage ring inverter based oscillator or 5 stage differential ring oscillator.For the former you need to just connect the inverters back to back, for the latter you need to set the gain of the differential pairs such that barkhausen criterion is satisfied.
Analog Circuit Design :: 29.08.2007 12:37 :: amarnath :: Replies: 14 :: Views: 3743
if three cmos inverters are connected one after the other, will the o/p be stabe or oscillating if the o/p of the last cmos is fed back to the i/p of the 1st cmos...
wat if 2 cmos n 1 cmos is connected in the same manner......
i think if 1 n 3 cmos is connected o/p is oscillating,and stable if this correct?..where does barkhausen criter
Analog Circuit Design :: 16.10.2008 12:17 :: sarika :: Replies: 2 :: Views: 680
Thanks for the paper. One small question... we know for oscillations to begin other than barkhausen criterion a startup criterion is also required... Is there a relation for the Ring VCO.
Analog IC Design and Layout :: 20.10.2008 11:59 :: steadymind :: Replies: 3 :: Views: 2007
An oscillator delivers some kind of energy. Where does it come from ?
Answer: Such a passive RC circuit as shown in the link has to be combined with an amplifier in order to work as an oscillator. This passive ladder has the task to produce at a certain frequency a phase shift of 180 deg. Combine it with an inverting amplifier (with the appropriat
Analog Circuit Design :: 01.09.2009 03:20 :: LvW :: Replies: 1 :: Views: 1663
My question may be absurd but can anyone tell me whether we can apply Barkhusen criteria for astable multivibrators? If it is possible,how?
No, you can't.
The reason is simple: The barkhausen oscillation criterion is based on the loop gain of a circuit with feedback. Any "gain" by definition is a small signal par
Analog Circuit Design :: 18.01.2010 10:38 :: LvW :: Replies: 1 :: Views: 991
What's the matter...wrong forum?
OK, I´ll try to give you some hints.
In general, you have two alternatives to analyze the CLAPP oscillator:
a) The circuit is considered as a two pole oscillator based on the negative resistance principle. In this case, there is no "barkhausen" criterion because this condition is
RF, Microwave, Antennas and Optics :: 14.03.2010 17:22 :: LvW :: Replies: 3 :: Views: 2162
Thank you ajishgopalr for this video i need more and more explanations
Shahabaz, it is not possible to explain here the oscillation principle in detail.
*Just some basic rules: The keyword for an oscillatory circuit is "positive feedback". That means, you have to connect an amplification unit (gain A) and a passive
Electronic Elementary Questions :: 15.02.2011 04:22 :: LvW :: Replies: 4 :: Views: 586
When we design an oscillator, sometimes we design in terms of voltage, then we have to satisfy the barkhausen criterion: gain * feedback = 1. In this condition, feedback is mandatory.
But we also use the reflection coefficient to design an oscillator, in which case we have to satisfy the following:
Γin * Γs = 1. And usually in this co
RF, Microwave, Antennas and Optics :: 19.03.2011 05:23 :: lamchidinh :: Replies: 7 :: Views: 638
The barkhausen criterion requires a loop gain of equal or larger than unity and a phase shift of 360 deg at a certain frequency.
In a typical ring oscillator the loop gain always is larger than unity. Each stage has an inherent delay, which can be increased using external capacitors.
There is one particular frequency Fo for which this total delay
Analog Circuit Design :: 20.07.2012 15:49 :: LvW :: Replies: 3 :: Views: 487
According to the bode plot of the loop gain, at low frequency, the phase shift is 180 degree, while its gain is well above 1(0dB).
It is unstable when we refer to barkhausen criterion.
Will the low frequency component oscillate?
I have seen a similar question in here but the answers in that thread is really chaotic. So
Electronic Elementary Questions :: 29.03.2014 05:13 :: LvW :: Replies: 4 :: Views: 340
I suppose you misunderstood the meaning of the gain margin.
The original circuit is stable with a gain margin plus 7.6 dB (because at -180 deg the gain falls below zero dB) - that means you have to increase the gain by 7.6 dB to reach the stability limit.
That means: Under these conditions (stability limit) your circuit - after closing
Analog Circuit Design :: 10.04.2012 11:55 :: LvW :: Replies: 16 :: Views: 578