Questions tagged [stability]

The tag has no usage guidance.

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

Control Loop Stability - Crossover frequency

I am testing the control loop stability of a DC-DC Converter. One of the Pass-criteria of the DC-DC Converter states, "Cross over frequency should not be higher than 1/8th of switching frequency" ...
0
votes
0answers
37 views

Why does continued fraction expansion work? [migrated]

While checking whether the given polynomial is Hurwitz or not, we perform continued fraction expansion. We were taught how to perform this check(i.e) look at the sign of the coefficients of the ...
0
votes
0answers
36 views

What is the Rseen from this node?

In the text book I am reading (CMOS Analog Circuit Design by Razavi) the author wrote that the Rseen from node N is (1/gm7), however when I derived it myself I found that the Rseen is ro4 // ro6 (...
1
vote
1answer
42 views

Question about feedback in a current reference

I'm studying the following Vbe-based current reference: The author of my book says: Observe that the circuit has two feedback paths around the gain stage. One positive, the other negative. ...
0
votes
0answers
48 views

Unstability condition for positive feedback network involving phase change

For positive feedback: \$G=\frac{A}{1-AB}\$ According to Wikipedia, this system is unstable for AB>1. This condition appears to be for the cases when 'A' and 'B' have real values. But in general, A ...
0
votes
0answers
36 views

Gain margin using Root locus plot

How can I find Gain margin of any control system given its polar plot In schaum's series I have read that Gain Margin=Ku/Ki but in given figure the system never becomes unstable so shouldn't Gain ...
0
votes
0answers
59 views

Opamp isolation resistor calculations for a capacitive load

I want to add a capacitive filter for pulse shaping to the output of a transimpedance amplifier using an OPA847. Without the filter, the amplifier works great. With the filter, I get some ...
0
votes
1answer
45 views

Abuse TS339 comparator channel as a voltage multiplier

I have multiple free channels of a TS339 amplifier remaining and would like to use one of them to multiply voltages like this: simulate this circuit – Schematic created using CircuitLab Now it'...
2
votes
2answers
45 views

MOSFET Capacitance clarification

2 part question here. Are there ways to directly test the input and output capacitance of a MOSFET, Ciss and Coss? On that note, due to internal inductance and capacitance, is it possible for a ...
0
votes
0answers
30 views

Phase margin Vs damping ratio: Intutive explanation

While designing the compensator for SMPS we always talk about the relation between phase margin and damping factor( or Quality factor). I don't completely understand how damping plays such a keyrole ...
1
vote
2answers
57 views

Stability and Positive/Negative feedback

I often read that positive feedback is used to get oscillators (since the output of the circuit is summed up to its input signal and so leads to instability), while negative feedback to get amplifiers ...
1
vote
0answers
54 views

Understanding a ZVS Oscillator in-depth

For a project I've been building, I've been using the (overused) ZVS oscillator that can be found online. So far it's been working great transferring power wirelessly, but I'm interested in ...
1
vote
0answers
31 views

Stability of Buck Converter when output capacitance is variable

I am designing a buck converter for an application that has several different loads. Depending on what devices are connected, the capacitance seen at the output of the buck converter can vary ...
1
vote
3answers
102 views

Bandwidth and stability of nonlinear circuit

I'm designing an antilog amplifier which produces an exponential output (0.4 mV to 4 V) for a 50 Hz sawtooth input waveform (4 mV to 4 V ramp). If this were a linear circuit, I could determine the ...
2
votes
3answers
105 views

LED brightness stability issues - how to fix?

I am performing an imaging experiment in which LED stability is critical. I use 2-3 red LEDs to illuminate a surface while imaging that surface. In each LED circuit, I use a constant-voltage ...
0
votes
4answers
94 views

Negative feedback and op-amp poles

I'm trying to get a better understanding of frequency compensation for op-amps. I'll start off with a very specific questions and then get into the context. For a certain op-amp, open loop gain is ...
0
votes
0answers
140 views

Could i get some circuit design feedback?

I have a computer science background and this is the first circuit I've ever designed. It is a lot of fun designing these circuits, but it also always feels like I'm missing a lot of "obvious" common ...
0
votes
0answers
39 views

Voltage regulator feedback circuit and stability analysis?

I have been analyzing following buck-regulator circuit to calculate the phase-margin and gain-margin. Circuit Diagram: Buck regulator with input voltage = 12 V and output voltage = 3.3 V. Just as ...
0
votes
0answers
67 views

What is the importance of Lyapunov stability for non linear control?

I understand that studying stability gives a particular region from which if we start it will converge to an equilibrium point. But why is the study important specifically for designing non linear ...
9
votes
3answers
349 views

Opamp stability given in not inverting configuration

If a datasheet (like AD828) says that an opamp is stable at Gain >2 (or reccomends to work with G>2, hence it is clearly not unity gain stable), what can we deduct about its stability in the inverting ...
1
vote
1answer
69 views

Stability Current Sink

I’m currently trying to create a programmable current sink. And I’m still trying to build up my circuit and searching for new parts. As I was searching for a OPA, I encountered much information about ...
0
votes
3answers
306 views

Effect of RHP zeros on stability

Why do zeros in the right half of the \$s\$ plane reduce stability (i.e., gain / phase margin)?
0
votes
1answer
105 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-...
50
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
38 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
104 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
42 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
83 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
54 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
272 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
104 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
82 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
88 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
92 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
87 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 ...
1
vote
0answers
58 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
68 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
107 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
169 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
68 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
123 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
89 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
320 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
282 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
189 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-...
4
votes
2answers
2k 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
117 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
761 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 ...
0
votes
1answer
96 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
138 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 ...