Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [stability]

The tag has no usage guidance.

0
votes
1answer
81 views

Stabilize circuit on 5V 2A

I have not yet build following circuit: Circuit in high performance needs 5V 1.7A (measured). I have source which is powerbank with 16 000 mAh. Outputting via ports: USB-C 5V/3A, USB-A 5V/3A, Micro-...
48
votes
5answers
6k views

Why does music synthesizer built from chain of astable multivibrator circuits get “out-of-tune” after a few hours?

I built a prototype keyboard/sound synthesizer using a chain of 13 astable multivibrator circuits whose outputs are connected to an audio amplifier chip (LM386) and speaker, all powered off a 9V DC ...
0
votes
1answer
25 views

Stability Criteria of Type 3 Digital PLL

I suppose we can derive the stability criteria based on poles of open-loop transfer function of F(z) in expression (4.11). However, the pole analysis does not help in deriving the stability criteria ...
1
vote
2answers
67 views

Is this mosfet stable? Trouble with capacitances

I have the following circuit and I'd like to know about its stability : From what I've learned from basic electronics courses, the first step is to add the parasitic capacitances. I know there is ...
0
votes
0answers
30 views

Questions about stability circle and impedance matching

I'm a RF circuit beginner and got stuck in stability related issues. According to Pozar's textbook, output stability circle is a contour in the "gamma_L" plane and its arc represents the "gamma_L" ...
0
votes
2answers
65 views

Does the stability of an LTI system depend on the input?

Consider a system \$G(s) = \frac{1}{s}\$. It is marginally stable, as it has its only pole at \$s=0\$. However, if we apply a step input, the output is \$ tu(t) \$, which turns out to be unstable. ...
0
votes
0answers
45 views

Understanding Optimization/Realization of the voltage controlled current source

I am unable to make a voltage controlled constant current source. So I am using the following scheme (Sorry for bad sketch drawing): The constant control voltage varies in the range of 0 to 5 V is ...
1
vote
2answers
88 views

Stability at loop gain <1 and 180 degree phase shift

I'm reading this article about stability of OpAmps: Link to article. It says: "If Aβ is less than unity at the high frequencies where phase shift reaches 180°, the high-frequency phase-shifted ...
2
votes
1answer
85 views

According to the Nyquist criterion this system is stable but when I apply an impulse I get an unstable response, why?

I have this open loop transfer function and I have to study the stability of the closed loop transfer function using the Nyquist criterion. What I got is that the characteristic equation 1+GH(s)=0 has ...
0
votes
2answers
46 views

Series voltage reference unstable with a series resistor

I am using the MAX6035 as a 5V reference that draws 5mA load current. To protect the input from transient spikes, I thought a simple resistor and zener diode circuit would work well. I noticed that ...
0
votes
2answers
65 views

Nyquist Stability Criteria

Find the stability where: Find the stability: \$ G(s)= \frac{(s+3)(s+5)}{(s-2)(s-4)}; \$ \$ H(s)= 1; \$ I run this code in matlab: ...
2
votes
2answers
83 views

How does transistor bandwidth affect stability?

I was watching a video where Dave Jones of EEVBlog interviews Rod Elliot of Elliot Sound Products. Rod was discussing that he tends not to use digital chips in his designs because the chip will become ...
0
votes
3answers
72 views

induction motor stability

Does the change in slip (s) have any impact on load torque in an induction machine/motor? I know it affects the motoring torque. But do the load torque also get affected by the slightest measures if ...
0
votes
0answers
49 views

Derivation of stability criterion for type 3 digital PLL

Could anyone help to derive the following expression (4.23) which is the stability criterion for type 3 digital PLL ? Note: Screenshots are taken from Floyd Gardner's book : Phaselock Techniques 3rd ...
0
votes
2answers
62 views

Cap maximum wall outlet voltage

I live in a rural area. A problem occured when my UPS could not run my computer simply because of voltage fluctuations. I have tried many stabilizers but its too rapid that it would make a tick and ...
1
vote
2answers
65 views

Determine the value of a constant for which the system is marginally stable

So I have the following transfer function $$G(s)=\frac{s^2+0.1s}{10s^3 + 1.1s^2 + 0.01s + 2K}$$ Now I'm trying to determine the value of K so that I have a marginally stable system. I'm not supposed ...
1
vote
3answers
77 views

Stability of op-amps: “Oscillations if phase = 180° and loop gain > 1” question

I'm trying to understand the stability against oscillations for op-amps in a feedback circuit. A common argument I've seen on many sites goes as follows: The closed-loop gain is given as $$A_{\text{...
0
votes
1answer
47 views

Constant DC Load Stability and Bandwidth slewrate

For this circuit, how do I know if the rise edge was limited by slew rate or bandwidth? What's the effect of R2 and C2 on bandwidth? -3db of this circuit in simulation is 649 kHz, I know in ...
0
votes
1answer
73 views

loop gain, open loop gain of op amp in inverting configuration (feedback capacitor)

I was trying to understand the 2nd answer from this post here, with the circuit of the post shown below. The 2nd answer has equations including open loop gain I wasn't able to understand (1st ...
1
vote
1answer
50 views

Determining Phase Boost needed to Compensate SMPS

I'm attempting to find the Control-To-Output Bode Plot (open-loop) of a SMPS designed around the TPS54160 so that I can design the type II compensator. The first step in designing a compensator is ...
0
votes
1answer
110 views

AD4610 - Is it possible to eleminate this single overshoot

I am trying to compensate input capacitance of the AD4610. It does not matter if it is actually over- or undershooting - there is always a spike: I do not have this problem with the OPA4141 for ...
1
vote
2answers
147 views

PA92 OPAMP phase compensation

I'm having trouble to understand the phase compensation on the PA92 opamp. First I'll explain quickly the circuit I'm building.   1.  The circuit I'm using a 200V battery and would like ...
0
votes
1answer
102 views

Loop Gain and Phase Margin Correlation

I have found a definition of phase margin of amplifier system from Texas Instruments application report. This definition looks like this: $$\phi = tan^{-1} (A \beta)$$ where \$ A\$ is amplifiers open-...
3
votes
2answers
946 views

Non-inverting op-amp configuration with capacitor

I don't really get what is the purpose of the capacitor C1 which is connected in parallel with the feedback resistor. After my knowledge, if we modify the input signal frequency the over all gain will ...
1
vote
1answer
106 views

LT spice not predicting instability

I'm trying to make a linear regulator using an op amp and a pass transistor. Here is the circuit: From my limited understanding you can predict the stability of the circuit's feedback loop by ...
1
vote
2answers
322 views

Op amp driving a LED oscillates, how to stabilize?

I have a simple LED driver circuit like this: simulate this circuit – Schematic created using CircuitLab The op-amp is OPA354 250-MHz, Rail-to-Rail I/O, CMOS Operational Amplifier supplied ...
1
vote
0answers
29 views

Why is it always the odd row that becomes zero in the routh hurwitz array?

A row becomes zero when a purely even or purely odd function is a factor of the characteristic equation. A purely odd function is just a purely even function multiplied by s. $$ q(s) = s^5 + 4s^3+ ...
0
votes
1answer
69 views

Compact thermostat for VCO temperature stability

So I have a voltage controlled oscillator with an exponential input made using the THAT2181 VCA IC. The schematic is shown below - the THAT2181 IC is used to change the C4 capacitor charging current ...
1
vote
2answers
85 views

Meaning of the “pole” of a transfer function with time delay

I learned in basic control theory that we can determine the stability of an LTI system by the signs of the real part of the poles of its transfer function \$H(s)=\frac{N(s)}{D(s)}\$. For a rational ...
1
vote
3answers
158 views

Crystal's ESR or Frequency Stability/Tolerance, which is more of a priority?

I'll be using a 12MHz crystal, CL=20pF on an NXP chip. Currently choosing between lower ESR (60ohms vs 100ohms) or lower stability (50ppm vs 10ppm). Which spec is more important? Should I choose a ...
0
votes
0answers
22 views

Current stability factor in terms of resistors in a biasing circuit

For the following biasing circuit: A text gives the stability factor as: Above S is defined as dIc/dIcbo. But how is the second equation above is derived from the first equation?(How is S is derived ...
0
votes
0answers
36 views

Buck/Boost evaluation board buzzing/ringing sound

I'm currently modifying this buck/boost evaluation board to output a range of voltages between ~1.5 V and 12 V. In order to achieve this, I've replaced R14 in the feedback voltage divider with a 20 ...
0
votes
1answer
42 views

What's oscillatory instability in the delay differential equations?

Does DDE’s stability depend on forcing term and ODE’s stability does not depend?If yes, then is frequency analysis of stability applicable only to DDE and not ODE? In control systems, we study ...
0
votes
3answers
441 views

Loop gain less than one is stable

So I read about Stability/Negative Feedback in amplifiers here https://www.allaboutcircuits.com/technical-articles/negative-feedback-part-4-introduction-to-stability/ I understand that an LTI ...
2
votes
3answers
253 views

Why is phase margin considered more important than gain margin in dc-dc converters?

Control theory text books say both gain margin and phase margin give information about relative stability. These quantities also give an idea about the corresponding closed loop system's transient ...
2
votes
3answers
81 views

Negative feedback sustainability

If positive feedback makes output exponentially increase and cause instability in an opamp then why doesn't negative feedback make output extremely small and cause the system to collapse?
1
vote
1answer
224 views

Why simulink step response differs from matlab's step function?

step response is different in simulink showing oscillatory behavior unlike in matlab step function Transfer function Step response Block diagram in simulink Simulink scope
-1
votes
2answers
59 views

What does asymptotic stability mean ? and can a system have lower than 90deg of phase margin and still be stable?

why bode stability criteria dictates 90deg of phase margin ? my understanding is that it is so when a system is cascaded with another there's a margin so the phase doesn't get to 180 and over, am i ...
0
votes
1answer
51 views

Gain of the amplifier

If we have open loop gain of 2dB or 3dB what happens if we use this in closed loop (except the gain reduction)..i mean how does gain affect on the output of feedback amplifier.
0
votes
0answers
68 views

1117 voltage regularo ceramic caps

I have made a mistake and I do not have the space on my PCB to add two serial resistors. Is it OK to use only one for two caps? Simulation looks OK but it only the simulation
2
votes
1answer
74 views

How can infer instability from the frequency response of control system?

When can we judge a control system to be unstable from its frequency response?.For example, thermostat computes the error signal (desired room temperature - actual room temperature) and then actuates ...
0
votes
1answer
60 views

Addition of step disturbance to a microgrid state space model

If we are having a microgrid model in the state space form as \$\dot{x} = Ax\$ where \$A\$ is complete system matrix.The matrix \$A\$ includes all the active power , reactive power, load currents, ...
0
votes
0answers
27 views

Is the “amount” of transportation lag is cause of instability?

Delaying a system may make a system unstable, as explained here. My doubt is, the instability depend on the amount of lag or not. Take the system with open loop transfer function $$G(s) = A e^{-Bs}$...
0
votes
1answer
121 views

Role of “a current-limiting low-inductance resistor”?

While reading some experimental setup of a paper, I've came across with a statement saying, "Since a DC power supply is not capable of finely regulating the discharge current at very low currents( in ...
0
votes
2answers
93 views

Stability of Feedback Amplifiers

I'm kind of confused above the stability of feedback amplifiers. Here's what I know In the notes, it says that I don't understand how that's true. I tried deriving it but didn't get anywhere
1
vote
1answer
316 views

Understanding the role of Pole zeros cancellation from the definition of stability

I have encountered the following theorem in a book. According to me, I can get an asymptotically stable system even if cancellations exist for the unstable poles. my example, Then Why does this book ...
0
votes
1answer
68 views

ESR of capacitor

ESR results in power loss and inefficient power supplies or regulators. How does ESR affect the stability of the system?
0
votes
0answers
32 views

Using vector diagram to explain stability in case of 180 degree phase lag and gain larger than 1

I am reading Control Loop Cookbook from TI but there are many confusing points. Hope someone could help me out. How can the loop be stable with 180° phase lag and gain much greater than 1? One page ...
3
votes
3answers
249 views

why large signal can make a conditionally stable system unstable?

This image below is from this TI cookbook. Please look at the red box. Question: why large signal can make a conditionally stable system unstable?
0
votes
3answers
213 views

Stability of a BIBO transfer function

Why is this transfer function unstable? The poles are 0 and -4, so they are in the negative half-plane, theoretically it was to be stable. Can anyone explain to me what makes it unstable?