Questions tagged [stability]

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64 views

How to stabilize this system?

I'm trying to understand system stability basics. Let us say I have a system $$ G(s) = \frac{500}{s^2 - 500} $$ Since it has two poles in the right half s-plane, it is unstable. How can I ...
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2answers
47 views

Resistor power rating and circuit stability

I've read the following excerpt from a book (Passive Circuit Analysis with LTSpice by Colin May page 96) but am not sure what that means (with no relevant explanation before nor after): On Fixed ...
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2answers
63 views

What is the significance of phase margin in an open loop amplifier?

I know the importance of phase margin to ensure stability in closed loop systems, but what about in open loop systems? I am designing a regulated common based LNA IC that operates in open loop. Can we ...
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2answers
44 views

Can a fixed output buck have too much output capacitance?

I'm working on a design with this buck regulator: tps62130 I'm using the 5V fixed output voltage version. I'd like to have significant capacitance on the 5V output because the device can be powered ...
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0answers
45 views

Stabilizing plot using root locus method

"Design a PI controller to stabilize the plant \$ G(s)= 1/(s-1)\$ using only root locus method." Since there are two variables \$K_p\$ and \$K_i\$ ,i.e. one for proportional and one for ...
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2answers
64 views

How to safely connect unused opamp stable for gain of +2

Please refer to AD828 or any other bipolar op-amp not unity gain stable. Which of the two below cases is better? Any other suggestion? Simulation suggests the second, but I need to understand if the ...
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2answers
63 views

What is the cause of this drastically different simulation behavior with slight variation in capacitor values?

This site uses Circuit Lab's schematic and simulation tool, for which I am grateful. Recently, I was attempting to modify a circuit present in this answer to a question. simulate this circuit – ...
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0answers
54 views

Oscillation frequency / criteria from Bode plot, negative feedback system

Got a question, which is very integral to a project that I am writing a report for (which I am to hand in soon, so in a hurry). Question: What will my oscillation frequency be? How will it be ...
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36 views

Non Minimum Phase Systems and Sensor Location

A stable minimum-phase system could potentially turn into a non-minimum-phase system after moving sensors to the AFT (behind) of the CG (Center of Gravity) of the vehicle 1. This is specifically ...
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1answer
76 views

Transimpedance amplifier oscillates

UPDATE: I have removed switch and shielded cables and improvised the board as shown in below image. The transimpedance amplifier is stable. I applied four signal of 10kHz, 1kHz, 1Hz and 100mHz of ...
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0answers
46 views

Bode plot multi phase margin

When bode plot have multi phase margin how to decide the stability the transient would effected by which phase margin
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35 views

How to quantify amplitude of oscillations in marginally stable systems?

A transfer function pole on the Imaginary axis indicates that the system is marginally stable which in time domain manifests as a sinusoidal motion with constant amplitude at the frequency of the pole....
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2answers
94 views

How is this pole compensated

I have an amplifier in a closed loop, the diagram looks as follows: The DC gain is simple which \$ -Rf/R1 \$. If I make \$ -Rf=2\cdot R1 \$ the the DC gain is two. This is verified using AC analysis ...
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1answer
37 views

Stability analysis of cross-coupled amplifier in Cadence

I am trying to implement a cross coupled amplifier with OP-AMP feedback. I am not able to get it stable for a square wave however. The circuit looks as follows: The OP AMP is ideal from Cadence, all ...
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0answers
116 views

Cadence gain and phase margin

I am trying to figure out the stability of an amplifier, for which I have to calculate the loop gain and make sure its not negative for instability. In Cadence one can use 'stb' analysis to calculate ...
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1answer
44 views

Problem with a tracking LM337 stability

I'm building a dual rail tracking power supply, for the negative supply because the current is not going to exceed ~200 mA I decided to use LM337 both for simplicity and stability of the circuit (so I ...
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1answer
50 views

Buck Converter Feedback Loop - Stability Criteria

Question 1 : I am having some trouble understanding the Stability criteria of the Buck Converter Loop Stability which says, "The cross over frequency should be less than 1/8th or 1/10th of the ...
1
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1answer
37 views

How Single Pole Switching of Circuit Breaker can improve the transient stability of the Power System?

There are numerous methods we can use to improve the transient stability of the power system. Visualization of methods like using fast excitation system, High-speed governors or using dynamic ...
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47 views

Why this stabilisation issue occurs for this waveform?

I'm using this simple wave folding schematic: This would be best described with two short videos. Both videos have triangle input into wave folder, and I am changing the amplitude with trimpot. First ...
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1answer
89 views

What information Bode plot does NOT present?

The classic Bode plot (2D Bode) represent value of the transfer function (a complex number) evaluated at \$j\omega\$ (imaginary axis). It provides information on system closed-loop stability margins ...
6
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1answer
206 views

Stability of input filter in SMPS - Theoretical explanation

I read the Application note Wurth Electronics ANP008c about negative resistance of a SMPS input and how to avoid oscillation when using an input LC filter. I'm asking for a theorethical clarification ...
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3answers
107 views

Amplitude stabilisation of LC oscillators

Like diode stabilisation and FET stabilisation in RC oscillators, what methods are used for the stabilisation of amplitude in LC oscillators? I have found it very difficult to obtain a clean sinewave ...
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1answer
57 views

Balancing a stick using two different designs and comparing both

I want to understand which feedback systems are in general preferred over another model (that I'm going to show in image),so first we take a example of a particular system (here stick at 90degree from ...
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52 views

How is this amplifier stable at 1GHz

The task is to design a amplifier for maximum gain, which means conjugate matching. The S-parameters at different frequencies are as follows Now for 1GHz $$K<1 \text{ and } \left|\Delta\right|<...
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0answers
72 views

Nodal voltage magnitude properties of electricity distribution networks

I am wondering how to know about an electric bus according to its measured voltage magnitudes (possibly and its corresponding real power injection profile). Following assumptions can be made: One ...
0
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1answer
55 views

Using single-loop analysis in multi-loop structure

Here is regarding Kenneth Kundert's explaination of the loop based stability analysis Two factors affect the applicability of this circuit: the local return loop inside the transistor and the reverse-...
3
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1answer
60 views

Small-signal analysis of transformer BJT oscillator

In an attempt to improve my circuit analysis skills, I've been trying to understand how this photo flash charger circuit works. I am mainly focusing on the oscillator part on the left, which I've ...
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2answers
118 views

Making a linear regulator oscillate

I want to make a linear regulator oscillate. ----------------------------EDIT------------------------------------ I change the PNP transitor by a PMOS and I corrected the polarity of the ideal opamp. -...
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2answers
72 views

How can I choose an absolute encoder with appropriate resolution?

I have a motor that runs between 3 to 3000 RPM. The drive update time is 2.2 micro seconds. What is appropriate an encoder resolution for this work (especially for lower speeds) so the drive could ...
1
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1answer
56 views

Digital control stability for more than impulse response stability?

I have a digital control system which is described by the transfer function $$ Y(z) = \frac{-\beta}{z - 1 + k \beta} X(z) $$ where \$\beta\$ is a real parameter I can adjust to modify the ...
0
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1answer
91 views

How to find gain and phase crossover from a Nyquist plot?

Note: I need to do this by hand which is why I'm struggling. I'm only using MATLAB here to show the nyquist plot, and I was also using it to try and check my answer. Edit: There are poles at -50, -10 ...
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1answer
102 views

Stability of passive networks

Generally we see that single Port electrical networks (LTI system) that contains resistors and other passive elements are stable . So is it safe to assume that passivity(absorbs power) of electrical ...
1
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1answer
39 views

Why does op-amp output impedance / parasitic input capacitance pole cause a noise peak?

I was simulating the above circuit in LTspice... I realize the main problem here is the 2MHz peak (which should be fixable with proper compensation), but I'm curious about the smaller 398kHz peak ...
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0answers
31 views

Transient and steady state of marginally stable system

I know that if a system is asymptotically stable then after infinite time its output contains only characteristic of input signal and it is also known as steady state and there are no transient ...
0
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1answer
60 views

Optimum phase margin Controller Design

I am designing a PI voltage and current Controller (Cascaded Control for Buck Converter with LC filter) and I am confused about what is the perfect phase margin to choose for the application. I read ...
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0answers
41 views

'Weaker' feedback reduces DC Gain?

My Understanding From my previous understanding of stability and op-amps, I know that placing an op-amp in a closed-loop configuration reduces the DC gain and extends the 3-dB bandwidth as seen in the ...
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2answers
67 views

SMPS stability near and above switching frequency

I am simulating in LTSpice a switched-mode power supply (LT3845) at a frequency of 150kHz. I am measuring the loop gain at the feedback node according to this article. The way I understand it, the ...
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2answers
56 views

About phase margin of inverting amplifiers

Phase margin is usually defined as how far is the phase of the loop gain from -180: $$PM = \angle \text({loop \space gain}) +180^{\circ} $$ Let's suppose that we want to compute the maximum phase ...
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0answers
33 views

Why can stability Factor be defined like this ? What does “stability” mean here? let voltage be stable? or let some of current be stable?

i saw some information about stability from here : https://www.youtube.com/watch?v=jw_GUiswndw&t=422s ,but i have some problems,why can stability Factor ,\$S\$, be defined like this ? \$S=\frac{\...
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0answers
22 views

PWM switch open loop gain plot buck topology

Open loop gain understanding, without using PWM switch and with using PWM switch model Vramp =1V , Vin =5V, Modulator gain = Vin / Vramp = 5 , Fsw = 300Khz, Vout = 1.8V Above image without PWM switch ...
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0answers
33 views

lyapunov function derevation

hi could you please help me to know how did they find the derivative of V lyapunov function
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1answer
47 views

Linear dropout voltage transfer function

I am reading this application note from Texas instrument : http://www.ti.com/lit/an/slyt187/slyt187.pdf?ts=1591543592096&ref_url=https://www.google.fr/. The application note give us the transfer ...
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3answers
171 views

LDO output and input capacitor clarification

I would like to understand how to size the input and output capacitor of an LDO. What I think to know: About the input capacitor: The input capacitor is used for filtering high frequency input ...
4
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2answers
130 views

Flyback - Stability, Oscillations, Buzzing

I'm working on a dimmable, 60W CV/CC LED driver (ILED = 0.7 - 1.5A, VLED = 40 - 85VDC). I'm having trouble with this driver since it has some issues including: Extreme buzzing (You can hear this from ...
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1answer
42 views

LDO datasheet dont provide open loop gain plot

To make LDO stable compensation. How to obtain open loop gain phase plot to compensate LDO, since it is not available in the datasheet. Since its very much required for LDO load transient, load ...
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1answer
70 views

Strange Error amplifier of LDO

I am trying to work out what function the components in inverter colors serve, this is a schematic I have derived from a net-list to make it easier to explain my answer ...
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1answer
62 views

Help check amplifier stability

I need to do the stability analysis of my amplifier circuit. I implemented schematic in LTspice, where I did some of simulations, so I would like to keep the same tool also for the stability analysis. ...
2
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2answers
103 views

Bias stabilization of a transistor

The instability of Collector current(Ic) of a transistor depends on three factors viz. Icbo, Vbe & Beta. Can you explain why Vbe decreases(by 2.5 mV/°C) with increase in temperature?
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3answers
54 views

MC34063A switching regulator: LC filter and feedback

The MC34063A bust/boost/inverting switching regulator recommends using an LC filter at the output, after the filtering cap. This LC filter is optional and there is no mention in the data sheet about ...
2
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4answers
242 views

Audio power amplifier improvement

I need someone to revise/suggest improvement for the audio power amplifier I am designing. This PA is going to be used for driving the horn speaker (8ohm 100W). I decided to start design from scratch ...

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