Questions tagged [stability]

The ability of an electrical circuit to stop oscillating within a finite period of time. Related topics include the Nyquist stability criterion (and the associated Nyquist plot), Bode plots, and gain and phase margin.

Filter by
Sorted by
Tagged with
0
votes
0answers
32 views

Phase lower than -180 when reaching unity gain, is it unstable or can we substract 360?

I am getting a phase of -434 degrees when reaching unity gain (0 dB point). The phase curve starts at 0 degrees, thus, can we consider that -434= -434+360= -74 degrees and the phase margin is of 180-...
1
vote
2answers
59 views

Caveats of the RC phase shift oscillator

I was reading some articles online where it talked about this kind of RC oscillator. I just want to clarify some caveats about this circuit: From: https://learnabout-electronics.org/Oscillators/osc31....
2
votes
1answer
119 views

Understanding on frequency compensation on driving capacitive loads with an op-amp

I am trying to understand an example circuit of frequency compensation on driving capacitive loads with an op-amp from: https://www.allaboutcircuits.com/technical-articles/how-to-drive-large-...
-1
votes
0answers
25 views

Using Duhamel's principle and impulse response for solving an inhomogeneous LCC ODE

Consider a system modeled by an \$n^{th}\$ order linear constant coefficient (LCC)* ordinary differential equation (ODE) with (a) Initially relaxed conditions with \$(y(0), y'(0), ... y^{(n-1)} (0)) ...
0
votes
2answers
57 views

Reduce hard voltage drops on mains? [closed]

I'm experiencing some hard voltage drops on my AC power line (measured at 20 points across the house). The culprits are the washing machine and dryer (as well as our upstairs neighbors washer and ...
0
votes
0answers
34 views

Are there common circuit stability issues at low current levels and/or recommended minimum values?

I'm building a small semi-permanent solderable PCB circuit using a couple of mosfet inverters, plus some resistors for voltage division and pulling inputs/outputs high/low. The final location will be ...
1
vote
1answer
60 views

LDO minimum current requirement

Is it good practice to use resistors (parallel to load) on LDO output? The MIC29302WU LDO I've bought has ~7 mA minimum current requirement for stability reasons. What other/better options I have? (...
1
vote
2answers
71 views

Will adding a pole in the loop gain make the system more unstable?

In the design above, the circuit designer added a low-pass filter in the feedback path of the op-amp for loop stability. Won't adding a pole to the feedback factor actually make the circuit more ...
1
vote
1answer
47 views

Bode plot starting from 180?

This is an NMOS common source amplifier and I'm trying to calculate the Phase Margin, but it's starting from 180 instead of zero? dose it mean I have poles at the origin or it's very stable?
0
votes
0answers
83 views

Nyquist plot - is my system stable?

I am working on a balance controller for a robot. I have obtained a transfer function between the robots motor voltage and the robot pitch angle. $$G= \frac{ -5.893e05 s^4 - 7.71e08 s^3 - 1.435e11 s^2 ...
1
vote
1answer
60 views

Measuring Allan Variance

I have some microcontrollers with TCXO's where I wish to measure their frequency stability using Allan variance (from say 1ms to 10s). However, my measurement equipment is limited. I have access to a ...
0
votes
1answer
42 views

How to guarantee the stability of a RF closed loop amplifier with inner loops?

I've a 3 stage closed loop amplifier with many loops inside of which some loops cannot be broken, to analyze the loop gain, as the parasitic capacitors are intrinsic to the device. What is the method ...
0
votes
1answer
59 views

Real/Complex Zeros for Filter Transfer Function

So I've been reading into filter design and came across how to determine the transfer function of a filter, when given it's poles and zeroes. I've come across the following question that has me a bit ...
0
votes
1answer
88 views

Analyzing effects of sixth order transfer function

This question is in relation to this question asked before (Settling time of sixth order denominator transfer function), but formulated in greater details. So I have a transfer function which looks as ...
0
votes
3answers
126 views

unstable systems with positive phase/gain margin

Open loop Phase/Gain margins provide information on how much margin the closed loop system have until it becomes unstable. In other words, how much you can increase the effective loop gain and or ...
1
vote
2answers
53 views

Modeling MOSFET Pole and Transconductance for use in Larger Overall Control System

Recently I began a project involving some active current limiting using a MOSFET and an Op Amp. It is part of a larger overall circuit involving other Amplifiers. I would like to perform a block-...
0
votes
0answers
28 views

Stability of circuit with amplifier with filter and impedance matching on input and output

I recently asked a question about an amplifier with impedance matching at the input and output of the circuit. Now that I know the matching is greater, I wanted to generate a Smith chart regarding the ...
0
votes
4answers
103 views

Why are identical value vs different value capacitors between positive and negative voltage supply leads?

I understand why various different value capacitor are added in low voltage power supplies....to be able to respond and absorb various size/frequency spikes. But why are there also identical value ...
1
vote
0answers
47 views

How does this compensation network work?

By accident I stumbled upon this Linear Technology application note (LT1074/LT1076 Design Manual): https://www.analog.com/media/en/technical-documentation/application-notes/an44fa.pdf Just for fun I ...
1
vote
2answers
115 views

Closed loop system stability with Bode

Stability of the closed loop system (with -1 feedback) can be assessed via Bode plot gain/phase margin analysis of its open loop system. How can one deduce stability of the closed loop system directly ...
1
vote
1answer
56 views

Why is the slope of the op amp graph 20 log (AB) in this application note

I am going through the following guide for op amps : http://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf On page 87 (screenshot attached) there is a bode plot which has got me slightly ...
1
vote
1answer
37 views

HSPICE create a voltage source in top level and instantiate it in a .subckt

I am fairly new to HSPICE and I am investigating someone else's testbench and I am trying to track down where is the vsource generator used in the .lstb analysis in this testbench. I am a bit ...
3
votes
2answers
55 views

Does a Lyapunov Function derivative necessarily vanish at each equilibrium point of the system?

From Jean-Jacques E Slotine's book "APPLIED NONLINEAR CONTROL" "several Lyapunov functions may exist for a given system, and therefore several associated invariant sets may be derived. ...
0
votes
1answer
66 views

How to prove a system is stable if the characteristic equation have non zero positive coefficients?

I read that a control system would be stable if its characteristic equation has got all the terms present and are positive. But I could not find any proof to it. How does one prove it?
0
votes
2answers
138 views

20 dB/Decade - Justification

I've read that it is recommended to have 20 dB/Decade slope on the L(jw) magnitude plot of the Bode Diagram at gain crossover. This seems to imply a slope of -1 in dimensionless terms. However, what ...
3
votes
2answers
156 views

A mistake in “Op Amps for Everyone” about op amp attenuators

In Texas Instruments' book "Op Amps for Everyone" (5th edition, link, see page 347), in chapter 25 "Common Application Mistakes" I believe there is a mistake (ironically). It ...
0
votes
1answer
60 views

What causes the Inverting input of this op amp to conduct current?

When I analyse this circuit to understand it's working, I got stuck at one point. Have a look on this circuit. When the feedback resistor value is 2.2k as shown in fig, I got the expected output with ...
3
votes
1answer
82 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 ...
0
votes
2answers
50 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 ...
1
vote
3answers
96 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 ...
1
vote
2answers
54 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 ...
0
votes
0answers
49 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 ...
2
votes
2answers
73 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 ...
0
votes
2answers
67 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 – ...
0
votes
0answers
66 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 ...
1
vote
0answers
40 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 ...
0
votes
1answer
107 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 ...
0
votes
0answers
50 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
2
votes
0answers
39 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....
1
vote
2answers
100 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 ...
0
votes
1answer
82 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 ...
0
votes
1answer
520 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 ...
0
votes
1answer
70 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 ...
0
votes
1answer
55 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
vote
1answer
51 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 ...
0
votes
0answers
50 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 ...
0
votes
1answer
95 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 ...
7
votes
1answer
463 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 ...
0
votes
3answers
167 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 ...
0
votes
1answer
58 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 ...

1
2 3 4 5
7