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How to stabilise the BJT diff. pair feedback loop?
I need to remove the oscillation of feedback loop while fast response is maintained.I have no problem to avoid the oscillation if 47 nF cap is placed across output but since I want to feed the input...
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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...
View ArticleHow 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...
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Common-collector Colpitts oscillator - feedback analysis
I am a student working on a project where we are using CC Colpitts oscillators as local oscillators.We've chosen the above values based on the condition gm> w02C1C2RL,series, which for the given...
View ArticleHow to add feedback system for a CNC machine which drived by stepper motor?
I have an old CNC machine to retrofit. In this machines stepper motors without are used and those motor are not double shaft, so how can I make a feedback for this system if it is possible?
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How to calculate the current and voltages of this Sziklai pair?
Im new to Sziklai pairs and could not find any information on how to do calculations for this case. Im trying to do DC calculations and the info i have : +IN and -IN are for AC source, the +VE and -VE...
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Phase shift near saturation mitigation in input stage amplifier -- How does...
I'm trying to understand how this circuit works on the input stage to the 4192A Impedance Analyzer.Apologies for the quality... this is the best scan I could find. The design is furnished with the...
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Measuring flyback SMPS feedback loop response
I'm trying to measure the feedback loop on a isolated flyback SMPS. My goal is to determine the phase margin and 0 dB cross-over frequency.The most common circuit I have seen is the one recommended in...
View ArticleFeedback Circuit schematic to Control Theory block diagram?
I'm studying analog electronics circuit with feedback.I see that, during analysis, a useful abstraction over the schematic is the block diagram in control theory style, but I stuggle in deriving it...
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Non-standard injection point to measure loop stability of SMPS
I have come across this document https://www.ti.com/seclit/ml/slup386/slup386.pdf , where injection points for stability measurement are discussed in Fig.26.For point 3 it says: "Because the op amp...
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What is the recommended minimum DC gain for isolated switching power supplies?
I am studying one of Christophe Basso's excellent articles, where he describes the transfer function of the TL431 error amplifier in a Type II configuration (No Fast Lane configuration):$$|H(s)|=CTR...
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Feedback controlled by potentiometer
I'd appreciate some help with the following section in this question:Here's an attempt:Since it's shunt-shunt feedback I figured I could write:\$V_o/V_s=-10=A(R_1+R_2+R_L)/(1+AB)\$, where \$A\$ is the...
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Tracking / softstart & FB pin tricks
Here is the circuit under analysis:A few questions:Z_DRV is a signal from a DAC. From what I can understand, this signal is amplified by U28:B. This in turn causes the output of the switcher IC to...
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Why are non-inverting error amplifiers not used in opto-isolated switching...
I am studying the application of error amplifiers, and I have not encountered non-inverting error amplifiers so far.In practice, the goal is, of course, negative feedback. However, when driving an...
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Negative phase margin and misconception of the point of instability in...
PreludeConsider a canonical block diagram of a negative feedback loop with gain \$K\$, plant transfer function \$G(s)\$ and feedback transfer function \$H(s)\$: -Regardless of what functions K, G, and...
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Inconsistent Behavior of Active Low Pass Filter
For my project, I designed a circuit consisting of filters. I used multiplexers (MUX) to route the signal through different filters, and the output is read through an ADC. As part of this project, I...
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Plotting a Bode from a Transfer Function on Matlab
I need a bode plot for a transfer function from matlab which I never did before. I tried some examples but failed. How to do this on matlab?Here is the TF:
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How to add frequency control feedback loop to a circuit for an inductive heater
I am interested in a design made by an MIT student, Bayley Wang, several years ago for a 30kVA induction heater. One engineer on this site with professional expertise examined this circuit and...
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Voltage Feedback Location on LED driver
I am looking at the LED driver circuit using the LT8391 in the datasheet, and I noticed that the feedback voltage is sensed before the output current sensing resistor. I don’t understand why this is...
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Does anyone know a feedback circuit (or IC) for doing a high voltage...
My team and I are designing an induction heater, and I've been asked to look into resonance sweeping so the microcontroller controlling our application can automatically find the resonant frequency....
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Auto-Shutoff Circuit for Variable Power Supply Controller
I'm working on an upgraded version of a circuit I developed to hack a potentiometer controlled variable power supply, allowing the output voltage to be set by a microcontroller.The basic circuit I...
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Testing feedback functionality of a PID controller
I have built an LTspice simulation of a PID controller based on this youtube video.The basic schematic is presented. The AD797 model was used to construct all the blocks.A PID controller was built by...
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Feedback issue using LTM8055 Buck-Boost Converter
I am trying to design a power supply for home by using a feedback system to the LTM8055 buck-boost converter. I have a 12V AC/DC converter that I want to use to convert into a voltage of my choosing.To...
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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 pin...
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How to determine DC voltage set-points (i.e. gain) of Op-Amp with JFET in...
I am working with a circuit design that I have never seen before - my understanding is that is derivative of an audio signal amplification circuit, but the history is unfortunately lost to time. We are...
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Positive feedback loop in the Wien oscillator
Let's say you got this circuit given which works as a Wien oscillator. To my understanding here Ri is the negative feedback loop and the total impedance of R3 & R4 & L2 & R1 are the...
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understanding feedback dynamics in differential current sensing circuit
There is a very interesting circuit which is described in the article attached.I know that feedback is sensing and returning, we can sense current/voltage and return current/voltage.I am imagining...
View ArticleStabilization of the resonant frequency of an RLC circuit
I want to build a resonant circuit at 35 MHz with a Q factor as large as possible (ideally 100-1000). The main component is a capacitor made of 2 plates, located 500 microns apart and capacitance 0.1...
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Applying a voltage by DAC to a Feedback pin of a DC-DC controller
I want to design a variable output voltage in the following design:For having this variable voltage either I can use a potentiometer instead of R13 or I can apply a voltage by DAC to the feedback...
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Expanding BW using feedback
I have built the following two stage amplifier as shown below. In open loop I get 63 dB gain and BW about 3 kHz. When I tried to add a feedback resistor to lower the gain and increase the bandwidth as...
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