# Tagged Questions

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53 views

### Gate driver and instability problem

This is a gate driver circuit for a boost converter. However, there is one part that I don't understand. Could you explain it or give me some links so I can read up about that? Here is the part that ...
59 views

### Build own custom USB 'regulator' adapter board to solve Desktop boot hangs with KVM

My Desktop PC hangs in the BIOS boot phase when my KVM is attached. If I unplug the USB connecting the PC to the KVM, the PC boots without hanging. If the USB of the PC is connected directly to the ...
52 views

### Two DC DC converter with different output - In series or parallel?

Source: LiPo Battery (13V - 16.8V) Consumer #1: 5V (RaspPi) ~1A Consumer #2: 12V (variouse) 0-3A (plus ~1A if series) DC/DC step down: two LM2596 Which would be the better solution: LM2596 #1 on ...
44 views

### Stability of closed-loop systems at -180 degree frequency

Say e(t) is sine wave and y(t) is sine output. If y(t) has the same frequency as e(t) with phase shift of 180 degrees, we can only get stability of the system, if the gain of open loop at this ...
98 views

### Feedback loop-gain(beta) derivation for the inverting amplifier?

During my study on the negetive feedback concept, i observed that the beta derivation for the non-inverting amplifier is so evident which is just a potential divider voltage.But i am unable to find ...
48 views

### How does a magnetic ballast (large inductor) stabilize a negative resistive circuit (such as a fluorescent light)?

When reading about fluorescent lights, I noted many sources stating that a large inductor (the magnetic ballast) in series with a negative resistor (the light, in this case) will stabilize it by ...
124 views

### Meaning of zeros in transfer function

Can someone please explain, provide a link or cite a book where the properties of the zeros for continuous and discrete time systems are explained? I know that the zeros are the frequencies where the ...
66 views

### Negative feedback - equilibrium

I have a basic question regarding negative feedback and stability. As I've understood it, negative feedback is supposed to promote equilibrium. But suppose we have negative feedback loop block ...
71 views

### Open loop oscillating

Will an open loop op amp with negative phase margin oscillate? I understand phase margin is defined in closed loop transfer function with equating denominator to zero . But will an insufficient ...
26 views

### PSU Stability Measurement

The mathematics behind stability are crystal clear. I am very confused, however, as to how these measurements are taken in a real system. Specifically, say I have a power supply. How would one measure ...
60 views

### Stabilising a constant current load opamp feedback loop

I designed a constant current load around the ACS712 Hall-effect current sensor (module from eBay). This module gives a voltage output of 185mV/A superimposed on VCC/2. Its current range is +-5A altho ...
202 views

### Can a 7805 ever oscillate?

I see many references to input and output caps helping with "stability" and some outright references to preventing oscillation in both answers on this site, and even in some data sheets. I also have ...
66 views

### How do I calculate phase margin for a feedback amplifier

I'm learning analog design and can't seem to get a firm grasp on the concept of phase margin and wanted to ask a few questons: First Part: I understand that Phase margin is the difference between ...
67 views

### Nyquist criterion and the gain/phase margin of transfer function?

Now to determine gain/phase margin I need the bode plot. and to find the value of k such that the system is stable I have to do Nyquist criterion for the closed loop transfer function. (Question: ...
105 views

### Delay and Stablity in Negative Feedback Systems: Confusion-2

This question is in reference to my earlier question: Delay and Stablity in Negative Feedback Systems: Confusion In that question I wanted to ask why the second order system is always stable. But I ...
135 views

### Delay and Stablity in Negative Feedback Systems: Confusion

Below is a block diagram that shows an op-amp in negative feedback with feedback network made from resistive divider: The encircled block is Op-Amp with 1 and 2 as its inverting and non-inverting ...
50 views

### Amplifier with two-pole is unconditionally stable

This is from a lecture slide: Amplifier with a single-pole is unconditionally stable. Amplifier with two-pole is also unconditionally stable. Are these properties considered for ...
205 views

### Phase margin analysis of a [diy] PMOS LDO [with LTspice]

I'm somewhat familiar with using LTspice to do phase margin analysis for a classic i.e. obvious negative feedback path opamp circuit; in fact I've done that analysis successfully for fixing real opamp ...
71 views

### Modeling a feedback loop in spice

I'm having some difficulty with an asymmetric half bridge design. I've never been great with control loop theory, and I'm wondering what the best way to figure out the R and C values for the feedback ...
135 views

### Systems stability with zero poles

I have a rather simple question I would say. I know that systems having real poles to the right side of the plane will inevitably be instable (for LTI systems at least). But I'm confused with ...
448 views

### Using more than one voltage regulator in series

Is there any problem (in addition to a likely loss of current) in using more than one voltage regulator (L7812CV) in series? And is there a real gain in stability? I ask this because I 'm going to ...
93 views

### Step response of feedback system

We have a feedback system F(s) as in this figure: and this is the step response of G(s): and H=10. F(s): We got the root locus of the system F(s) as this: then we determined the gain ...
1k views

### Is it ok to clip component leads after soldering?

When working with through the hole components, I have read that you should clip leads before soldering so the shock from clipping doesn't break the joint. On the other hand I've seen a ton of ...
62 views

### Stabilize Vds with a clean voltage reference

I suppose we can simply stabilize V_ds using a voltage reference, like a zener diode (a very clean signal one) to stabilize a MOSFET and keep it from swinging it's Vds and therefore the Id and ...
499 views

### Can there be “too much” capacitance on a buck regulator output?

I've an MPM3610 buck regulator module with an integrated inductor of 0.47 ÂµH and a fixed internal compensation. It employs constant-on-time regulation. The datasheet gives some application ...
174 views

### Why do we take gain and phase margin from these points in stability?

In the following graph, why do we take the phase margin from -180 degrees and the gain margin from 0 dB in stability?
672 views

### Why are low-dropout (LDO) voltage regulators unstable?

LDO regulators based on P-type transistors seem to be the preferred form of linear voltage regulator today, but I keep hearing about how I have to choose the output capacitor(s) carefully to guarantee ...
6k views

### Gain margin and Phase Margin Physical Meaning

I have been trying to understand the physical concept of Gain and Phase Margin.From what I understand it a relative comparison around the critical point (-1,0) which when converted to magnitude and ...
46 views

### phase-stability two op-amps

I'm trying to simulate two op-amps back-to-back (G=30 each) in LTSpice and work out if they will be stable. If I look at the .ac analysis after the fist op-amp I have good phase margin (about 60 ...
70 views

### Control: what is the proper justification that you can't just make the output equal to the input if the system produces unstable output

Suppose we have a signal, it goes into the plant and generates an unstable response, a common question then arise at that point is why can't we just set our output to a "hard-coded" input. Think of ...
268 views

### Why 60% overshoot with 55° phase margin?

UPDATE: Based on the answers I received, I got this working beautifully. There's a full outcome report in one of the answers below. I'm working through the design of an electronic load, basically a ...
112 views

### Why does smaller step show instability better?

I was stability testing a simple op amp circuit by applying a square wave to the input and looking for ringing etc. on the transitions. I figured, hey, I'll give it a big whack, say from 0 to 5V, ...
95 views

### How do I determine $R_o$ for an op amp?

I understand that when driving a capacitive load with an op amp, the output resistance, $R_o$, of the op amp interacts with the load capacitor to form a low-pass filter, introducing a pole in the ...
58 views

### Stabilize a 12V DC supply (from Lipo)

I'm newbie in electronics, but I want to learn some basics things. I have a 12V DC output (from a charging/discharging PCB Lipo battery), and I would like to stabilize it to run a mini-amplifier ...
85 views

### Is it possible to describe an unstable circuit in VHDL?

i was reading this (VHDL: Signal assignment question) post and i got curious about an issue that i wander if it could arise writing VHDL code. Is it possible to write the code for an unstable ...
100 views

### What can be inferred from the frequency an op-amp is oscillating at?

For whatever reason, I seem to create a lot of oscillators in the course of developing circuits involving op-amps. I'm wondering if the frequency of oscillation, which normally appears to be quite ...
4k views

### Why is my circuit so incredibly sensitive to electric fluctuation?

I recently finished building a circuit showcased in a beginnerâ€™s electronics book. I have included the picture of my creation below because I think it may become relevant to the question. At the ...
117 views

### Step-down converter and ceramic minimum ESR capacitor

I'm building a step-down converter, based on the TI TPS5450, which provides a reference design and various considerations on the capacitor. Even on the minimum ESR required. But when states "The ...
40 views

### Explanation for stability criterium microwave amplifiers

Given a general microwave amplifier circuit For this amplifier (transistor) to be stable the the magnitude of the input and output reflection coefficient must be smaller than 1. But why? What is ...
467 views

### Alternative ways to maintain temperature stability of silicon BJT circuits other than feedback resistors

So I've been messing with Bipolar Junction transistors lately and I'm trying to really nail the concepts of designing circuits with these things cause I want to start using them in some of my circuits ...
512 views

### Phase Margin Criterion

Why is 45 degrees considered minimum phase margin. Is it just for stability considerations or some other reasons too? Thanks.
1k views

### Why is my op-amp oscillating?

I am attempting to build the following circuit using an LM6171 op-amp. I know that this op-amp is unity-gain stable. I previously had this circuit working with an LT1637 op-amp, but I had to switch ...
583 views

### Obtaining stability information from Bode plots

I am trying to understand the theory behind gain and phase margins from Bode Plots for systems with negative feedback, specifically this one: The transfer function for this system is:  ...
1k views

### What components or circuitry exist that can provide extremely high speed, accurate clocks?

I've been curious for awhile now about doing some high speed projects, such as measuring time differences of radio wave reception, and was wondering if there exists components that provide clocks much ...
57 views

### Feedback Stability Comparison [closed]

Compare the Feedback conditions given below in terms of stability:- Negative Feedback Positive Feedback with LoopGain < 1 Positive Feedback with LoopGain = 1 Positive Feedback with LoopGain > 1 ...
101 views

### AP5002 step-down switching regulator loop stability

Problem, parameters I have an 5V output power supply, with 2S LiPo input (6-8.4V), implemented with AP5002 (PWM control 2A step-down switching regulator, docsheet), and for the life of me, I can't ...
145 views

### Why would the Schmitt trigger relaxation oscillator a bit unstable?

This thing oscillates from time to time. Why? (Respect part numbers, all chips from NXP) simulate this circuit – Schematic created using CircuitLab ...
197 views

### Effect of zeroes in system stability

Suppose we have two third order systems (a and b), with three poles and two zeroes,poles for both the systems are at the same positions in frequency domain but these systems differ in the placement of ...