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32 Threads found on Stability Circle
I did the following simulation to get the source stability circle for the specific transistor (hp_sp_AT-41435_1_19921201). The plot I got for source stability circle is as fig-1 But the plot should look like as fig-2 Actually both of them are same plots. But in my case, the smith chart has been divided into two (...)
Hi all I am doing an assignment in LNA design. I was stucked up with drawing stability circle. I read the book RF circuit design by chris bowick. In that it was mentioned that to draw the stability circle find the center and radius of the circle with some formulas and to mark the center follow as if to (...)
i ve modified the msg as the previous one was wrong. was confused myself, haven't build a amplifier for many years. anyway, just a tips for you, it's much easier to confirm ur amplifier stability by drawing the source/load termination together with the stability circle (for each frequency), and to make sure that the source/load stay as far (...)
You have an excellent tutorial here: Look under RF & Microwave Theory - stability.
Try to add a small resistor value in source…just to see if you can stabilize. I know the NF will go up, but is an indicator. Usually, if for stability is looking for a high resistor value in source, means that the input match need a different topology.
S11 reflection coefficient of 1.2 is strange. Normally 0
It said that the condition of amplifiers' unconditional stability is K factor not smaller than 1 and delta(S) smaller than 1. But for my simulation, while this condition is satisfied, the load stability circle doesn't lie totally outside of Smith Chart. It means that the load does not satisfy the condition of unconditional (...)
Hello, Recently I have been having some difficulty designing a particular stable CC amplifier. Generally I just work with the amp until it is unconditionally stable and then I just calculate the simulatenous conjugate match or determine the load that will provide a particular gain from power gain circles. I have been trying to design a CC amp fr
stability circles are outside of the Smith Chart that's why ADS used extended Smith Chart. If a circle is outiside of the Smith Chart, there isn't any real impedance that makes your amplifier means your amplifier unconditionally stable. But make zoom and check other circles carefully.
u can use ads -s parameter-stability circle
Why you do not make an amplifier in these ranges, add positive feedbacks to move in stability circle of smith chart and make the oscillator? I know this way you can make the oscillator which will have frequency stability pretty nice.
if you don't know the ROC, it is generally impossible to say about stability. a transfer function may correspond to some stable and/or unstable functions.
Hi there! I need to design an amplifier using ATF-36163 transistor. I also have to use Ansoft Design (I have not really get the hand of using this yet). The amplifier is to operate at 5Ghz (that's the only requirement in terms of variables). I already have the S parameters in hand. However, I am quite lost on how to start. I have looked at t
Hi all, I am designing a LNA. In ADS I get the stability factor 1.004 and the stability measurement 0.391 but the stability circles (both source and load) include the whole Smith Chart! The stability factor and measurement say that LNA is stable, but the stability (...)
why it is necessary that region of convergence of any stable system must include unit circle in z plane?
To follow up: As noted K>1 says stability but give no hint at how far outside the smith chart the stability circles are. Similarly if you get K<1 it doesn't give you much insight as to what to do, or where to do it. On the other hand Mu and Muprime have direct relation and give great insight. Mu is the distance from the center of (...)
Do any stability test. Take reference from any control system book.
Hello, You said you designed means simulated or fabricated a prototype!!! The S11 can't be positive their may be some problem with the device model parameter or file... Yes, it is unstable (oscillations), plot the K or B1 stability factor plots or stability circle measurements on smith chart.... See more here
Good day, I am designing the front end for a 2m HAM radio. I have selected and bjt and simulated the load stability and found it to be unstable. I have chosen the method of a shunt resistor on the collector. The method requires me to plot conductance circles on the smith chart as close as possible to the plotted load stability (...)
Did somebody used AppCADS stab circles from S-param files? I can't see, or something looks wrong, or line instead of circle?!
I want to ask, are there any other cases than that: Output stability: 1) |S11|<1 2) |S11|>1 Input stability: 1) |S22|<1 2) |S22|<1, but Rin>|Cin| 3) |S22|>1 does this inversion rule "but Rin>|Cin| [stable inside circl
Hello Friends I need an emergency help. I am studying with amplifier design. I have a TI calculator with that I need to calculate lot of equations, those are below. 1. Reflection co-efficient 2. Impedance 3. Gain 4. Radius of stability circle 5. center of stability circle 6. K 7. Delta so on etc I (...)
Hi all,I wonder if somebody would like to help me with an optimization problem in Matematica. I have the so called S-parameters (S11,S12,S21,S22) of a transistor circuit and are complex valued. I want to maximize the trancducer powergain function Gt= *|S21|^2* Constraints: R_in= S11
Hi all,I wonder if somebody would like to help me with an optimization problem in Matematica. I have the so called S-parameters (S11,S12,S21,S22) of a transistor circuit and are complex valued. I want to maximize the trancducer powergain function Gt= *|S21|^2* Constraints: R_in= S
Plot the stability circles and then find the nearest circle to the center of the smith chart and then add either series or parallel resistance that will have a value whic cuts the vicinity of the circle... This is most basic method to obtain stability. In that case , the vicinity of the neares (...)
here is the openloop gain of a system. I am a little worried about the point A. at this point, the phase is around -160 degree. Does this have any impact on the performance or stability of the system? the system is using 100% feedback.
In case of DTFT of a system function, it can do the transform only if the h is a stable sequence Σh should be less than infinite. So we can take DTFT only for stable systems. But by using z-transform we can transform even the unstable systems and can analysis the stability criterion.
hi I am designing oscillator. i want to plot stability circles. coordinates that i got for input & output port of transistor are 1)for input centre = 1.77<83deg. & radius = 0.88 2)for output centre=32.32<-80deg radius = 33.07. how to plot this on smith chart.
if poles tells us about the stability of the system,what do zeros tell us about the system?
hi, I have a question about stability criterior in negative feedback circuit, i hope somebody who have read "Understanding delta-sigma converter",Temes,G.C. can tell me the answer.. In circuit theory, we know in a nagative feedback system,the loop gain L1(f) is stable if |L1(f)|<1 at 180 degree phase shit location,say f=f1, my question is:
the Z-transform is a complex transform deals with the explanation on impedance. here in your que z<|1\a| means your system transfer function will be convergent only untill your impedance value remains between the values of -1\a to 1\a. that means your system's ROC i.e. stability is inside the circle with radius 1\a.
Minimum phase polynomials have all there zeros inside the unit circle of Complex plane. In control theory and signal processing, a linear, time-invariant system is said to be minimum-phase if the system and its inverse are causal and stable. Not quite correct. Minimum phase systems must not have zeros in t