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Buck regulator's feedback voltage far lower than expected
Datasheets: Buck regulator: AOZ2261NQI-12 Inductor: PQ2614BLA-150KI am using the buck regulator to convert 24V down to 12V. However, I am seeing weird behavior where VFB is much lower than expected....
View ArticleDesign of feedback control systems [closed]
A unity feedback control systems for a robot submarine has a plant with a third-order transfer function G(s) = K / (s(s + 10)(s +50))We want the overshoot to be approximately 7.5% for a step input and...
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How are positive and negative feedback of opamps so different? How to analyse...
In an opamp, feedback on the positive input places it in saturation mode and the output is of the same sign as V+ - V-; feedback on the negative input places it in "regulator mode" and ideally Vout is...
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How to break the feedback loop and add the loading?
I am trying to break the feedback loop of a fully differential amplifier and add the loading to the input and output:I want to do this to take into account the loading of the feedback network on the...
View ArticleUsage of input voltages in ideal op-amp
Why is the difference between inverting and non-inverting voltages in an ideal op-amp equal to zero in many problems? I can't seem to get that.Let's say that if the difference voltage equals zero, how...
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How can I get the same equation when using feedback loop analysis?
This is the circuit:Formula correction according to @Puk. (Shout out to Puk!)$$V_{in} g_{m1} + \frac{V_{o}} {r_{o1}} = (V_{in} - V_o) s C - \frac{V_o} {r_{o2}}$$$$\Rightarrow \frac{V_o} {V_{in}} =...
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why is my analysis for this resistor \$R_F\$ feedback network different from...
The following is from the book Design of Analog CMOS Integrated Circuit, page 313.Calculate the voltage gain of the circuit. (channel length modulation and bulk effect are neglected)At Node X with the...
View ArticleStability test for Feedback Amplifiers
Does the following simple test deduced from Nyquist criterion also apply to positive feedback case or it needs to be modified?If magnitude of loop gain i.e. |T (jω)| > 1 at the frequency where...
View ArticleDesigning a PI controller for a first order system
I have a first order plant: $$ b/(s + a) $$That I'm trying to control using a PI controller:$$ \frac{(K_ps + K_I)}{s} $$I closed the loop with unity feedback to get this transfer...
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What is the feedback \$\beta\$ for this resistor feedback?
The first is the schematics from NMOS4 with parasitic capacitance:What is the feedback \$\beta\$ for this resistor feedback? And Should we include the capacitor \$C_{gd}\$ for this feedback?The...
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How to analyse this with nullor block?
The first is the schematics from NMOS4 with parasitic capacitance:I recently read an article on how to analyse the circuit with The Nullor and Some Applications.The equivalent nullor circuit. I am not...
View ArticleSine wave CMOS buffer from inverters with or without feedback
Is it possible to buffer a sine wave using inverters alone or with some kind of feedback?I've been browsing google for minimalistic (I'm in 3.3-12 V domain) sine wave buffers and this thought stuck in...
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Why did my matlab calculation simulation differs greatly in LTspice simulation?
Here is my circuit in LTspice.The frequency ac is here.This is DC with .op command. --- MOSFET Transistors ---Name: m1Model: nmos-shId: 1.91e-04Vgs: 7.96e-01Vds: 9.03e-01Vbs: 0.00e+00Vth:...
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Why does my MATLAB calculation/simulation differ greatly from my LTspice...
Here is my circuit in LTspice.The frequency AC is here:This is DC with .op command.--- MOSFET Transistors ---Name: m1Model: nmos-shId: 1.91e-04Vgs: 7.96e-01Vds: 9.03e-01Vbs: 0.00e+00Vth: 4.00e-01Vdsat:...
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Why will the offset of a source-follower which is connected to the output of...
I am currently reading chapter 12, "The Common-mode Feedback Circuit" in Analysis and Design of Analog Integrated Circuits by Gray and Hurst.Page 815, gives the following statement for improvement of...
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Unexpected oscillation when using op-amp positive terminal for feedback
I am simulating a simple constant-current source using LTSpice:In simulation and on the breadboard, this works as expected: U1 controls the M1 gate voltage, the voltage across R1 is a constant 5 V, and...
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How to compensate this circuit? [closed]
I'm using the circuit above to control the common-mode voltage of the 2 resistors. M16 is a current source. The OpAmp controls common-mode voltage by adjusting the resistance of M20.I need to adjust...
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Two port feedback analysis of shunt-shunt amplifier with unity feedback
To consider the effect of loading in a shunt-shunt amplifier that is being analyzed with two port analysis, we short the feedback network at the input/output to calculate loading at the amplifier...
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Deriving inverting op-amp configuration gain from feedback theory
I am trying to derive the gain of the inverting op-amp stage from feedback theory. I have done it for the non-inverting stage.I'm having some difficulty - how do I deal with the Vin in the feedback...
View ArticleBiofeedback device to monitor muscle tension [closed]
Some beauty-conscious people wear scotch tape at night to prevent frowning when they sleep.Apart from mechanically forcing their forehead muscles not to frown, what would be needed to make a device...
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