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Questions tagged [operational-amplifier]

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0answers
25 views

Gain bandwidth product of amplifier in a DC scenario

I think I have a simple (but still to me confusing) question regarding the gain bandwidth product (GBP) of an instrumentation amplifier: Datasheet (AD8237) I have sensors that change their output ...
0
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1answer
46 views

Why is one of the transistors in ROM sense amplifier twice the width of the one opposite of him?

The picture is of Sense Amp design of ROM component in which a 'dummy' bit line is used to imitate the current so that the proper information can be derived from the memory cell by comparing the ...
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4answers
141 views

Op-Amp gain calculation

I'm trying to find R4 that will make: $$\frac{V_{out}}{V_{in}}=-120$$ The operational amplifier is ideal. My attempt: In the '-' input there is a virtual ground, so the equivalent resistor above is ...
2
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1answer
65 views

Noise generator with LM318

I want to build a noise generator from a Zener diode. I designed the above circuit. The noisy voltage from the diode is filtered via a high-pass filter and input into a 92x gain non-inverting ...
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2answers
77 views

Figure of merit of Operational amplifier

How can I measure FOM(figure of merit) of an operational amplifier? There are so many parameters, how can I decide which formula to use while calculating FOM?
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0answers
32 views

Switch resistor with n-channel MOSFET not working

So I try to amplify a photodiode signal with an operational amplifier. As I want to amplify two signals (1 for a high-intensity light and 1 for a low-intensity light) I sort of need to design a ...
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1answer
71 views

Choosing the right capacitors and resistors for transimpedance circuit

I'm designing a circuit for a pulse watch. Therefore I naturally have an operational amplifier and a photodiode in my circuit. The job that I want the transimpedance amplifier to carry out is to ...
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1answer
78 views

Correct use of transimpedance amp

So I realized that it might become a necessity for me to use a transimpedance amplifier for a pulse watch that I intend to make. Some background: The pulse watch shoots light at 940 and 660nm at ...
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2answers
101 views

Finding Thevenin Resistance Amp Op

Hello folks, I've got some douts about how can finding the \$R_{th}\$ seen between \$V_{out}\$: A: is a amplifier gain The possible answer are: A) \$ R_{th} = (A.R_s)\$ B) \$ R_{th} = (R_s + A)\$ ...
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2answers
57 views

Mathematical model for differential signals and relation with reality

i have a question and i hope is not that strange. i spend some time asking myself how people came out with the mathematical model for differential signals and why is this better in this way?! to be ...
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1answer
45 views

LTSpice Operational Integrator not Working

I'm fairly new to LTSpice and I'm having a hard time making this circuit to work. So I'm making an Operational Integrator but my Output signal doesn't seem to match my predictions. If I'm not ...
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2answers
61 views

Why doesn't my operational integrator work?

Here is the schematic I'm following, to build an operational integrator. (Image source - Electronics Tutorials) I'm using a LM358N IC which has 2 op amps. Below is a crude drawing of my connections. ...
2
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1answer
74 views

Power Dissipation of Op-Amp

If we look at the output stage of the MP111 op-amp it's just 2 MOSFETs in series. I'm curious why the power dissipation of the device isn't simply \$R_{\text{ds(on)}} \times I_{\text{out}}\$, but ...
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3answers
58 views

Is this a true corollary about Ideal Operational Amplifiers?

I don't see how the 2nd theorem is true for an ideal operational amplifier. This was from the Engineering Circuit Analysis 8th Edition textbook by Hayt. If this is correct can you somebody help me ...
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1answer
156 views

Can't balance differential amplifier circuit

I'm trying to build a circuit which involves an Op Amp in differential amplifier configuration. However I've been having difficulty balancing my output. My understanding of the differential ...
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0answers
40 views

Window maker basic circuit question

I am in a basic electronic laboratory and we are working on an ON/OFF analog switch lab. Here the first subsystem is shown and basically it introduces the idea of a upper and lower limit window with a ...
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1answer
29 views

Removing/Subtracting Lead Resistance Using Op Amp Circuit

I'm working with RTD sensor, and need to use Op Amp circuitry. Can someone explain to me how this Op Amp circuit work to remove the lead resistance? So that Rw1, Rw2, and Rw3 vanish, hence the ...
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2answers
165 views

How to design a circuit starting from a block diagram?

I am struggling with the following self-study problem, taken from The Analysis and Design of Linear Circuits (8th edition). There are two things that shock me from this problem. We need to get a ...
0
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3answers
87 views

What's the first pin of OPA2365?

Usually I recognize the first pin of an IC by observing the small circle and then comparing it with the layout in the datasheet, but in the OPA2365 there is no circle. In the image, is the red arrow ...
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1answer
74 views

How can I use a comparator in a circuit?

I am learning about how to use Operational Amplifiers as comparators. I understand that comparators are used to compare an input signal to a reference voltage. However, I am having a hard time ...
0
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1answer
64 views

Analysis of a modified Howland Current Pump

I am trying to do an analysis of the following modified howland current pump based on the circuit description in the datasheet of the LMP7701. This is a voltage controlled current pump that is driven ...
0
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1answer
51 views

High gain amplifier ADA4528

I am trying to make an amplifier which should amplify signals from at least 10uV (lower better) to around 100mV or above. The signals range from a few Hz to around 100kHz. Adjustable gain is also ...
0
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1answer
78 views

How to use a CT to measure overcurrent?

I plan to use a CT to measure the current on a resistor whose voltage will be controlled by two SCRs in antiparallel. The main function of the CT is to detect an overcurrent in the system to proceed ...
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2answers
167 views

High-speed Infrared UART link with photodiode

I need short-distance (about few centimeters) wireless IR UART link with 250k+ baud. I tried to use phototransistor (assume Q1 is phototransistor). Q3 is used to prevent inverting signal. simulate ...
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2answers
586 views

How does a cross-over BJT's damp the distortion with help of negative resistive feedback in an analog audio amplifier?

I found an expression that explains how a circuit with op-amp responses to a distortion: $$y = \frac{1}{\beta}x + \frac{\delta}{A\beta} $$ Now consider the circuit: Here, the green, blue and red ...
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4answers
391 views

Are there any single supply OP amps with negative supply voltage?

I learned that basically the only difference between a "single supply" OP amp and a dual supply one is that the former can drive much closer to the negative supply rail. Furthermore if I understand ...
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2answers
93 views

Working with RF Amplifiers for the first time

I'm designing a circuit to use an IF amplifier, specifically the ADL5536, to amplify the signal of an SiPM array consisting of the MicroFJ-60035 TSV SiPM by SensL. My goal is to use this amplifier to ...
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0answers
47 views

Filter question, shelf or pass?

In the circuit below: I often see capacitors like C4 added in the feedback path of a non-inverting audio amplifier, and often times I heard that it acts like a high-pass filter. However... At ...
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1answer
41 views

What is the frequency response of a charge mode amplifier?

I'm having some difficulty understanding the frequency response of a charge mode amplifier, circuit shown in Figure 1 below. ...
0
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1answer
496 views

Op amp with potentiometer

I have to find voltage gain $$\frac{v_2}{v_1}$$ as a function of x in the following circuit: As far as i can see, this xR thing is obviously a potentiometer, usually, i would do this using ...
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2answers
84 views

Input Impedance of Noninverting Amplifier

I simulated a simple noninverting amplifier using an operational amplifier in LTspice and i was wondering about the input impedance. The input impedance of a noninverting amplifier should be the ...
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1answer
63 views

What is the maximum output current for a practical operational amplifier? [closed]

We have been given a table of electrical characteristics containing the values for the ideal and practical values of operational amplifiers but it does not include the maximum output current. What is ...
1
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1answer
98 views

Use Raspberry Pi to power a low noise inverting amplifier with negative voltage input

I am looking to use a Raspberry Pi to power and read the current from a current-to-voltage converter. I am currently using two batteries to power the operational amplifier, as shown in the schematic ...
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1answer
85 views

Why this operational amplifier is saturated?

my problem is that in this circuit: Where \$\pm V_{cc} =\pm 15V, R1=1k\Omega, R2= 10k\Omega\$, if I introduce a signal like: \$ v_i(t) = 2 \cos{(2\pi 1000 t)}\$, the output voltaje is this: Where ...
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0answers
48 views

Voltage Comparator simulation problem

Operational amplifier is used as voltage amplifier. Here, voltage V+ of comparator=4.78V. Whenever the capacitor charges initially with zero voltage and reaches the threshold(v+) the output goes low. ...
0
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1answer
40 views

what is the maximum load for an instrumentation amplifier, in particular the AD620?

From the reading of This datasheet, I can't figure out what is the maximum load I can put at the output. To make my question more precise, suppose I need a gain of 10 (for DC measurements), for an ...
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2answers
194 views

Kirchhoff's law when using an OpAmp

The blue text is mine and the black text is given by my teacher
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1answer
60 views

Misconception in opamp feedback

Is it a misconception that feedback into inverting terminal of opamp is negative feedback and feedback into noninverting terminal will be positive feedback? I feel it is. Because all oscillators have ...
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2answers
80 views

Transfer function of Operational Amplifier

I am trying to solve the following operational amplifier circuit to get its transfer function. I have tried two different approaches, one is elementary approach by finding V- and V+ and equating ...
2
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3answers
78 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?
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1answer
531 views

How to add dc offset and gain to a given signal

Before I start, I just want to mention that I am a premed student. However, I want to build a DIY amp for my headphones since my computer can't properly drive them so I decided to take an electronics ...
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4answers
708 views

Adding DC offset to a given input

let me start off by saying I am a computer science student so I'm not familiar with electronics whatsoever. Anyway, I am faced with this problem: I am given some input (say, a sine wave) centered on ...
0
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1answer
46 views

behavior of operational amplifier at 0V

I measured the turn-on and turn-off behavior of an LM741 and found a weird phenomenon I cannot explain myself. I built an inverting amplifier with an amplification of 10. Why is there such a weird ...
0
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1answer
81 views

Operational Amplifier and MOSFET

I draw a new schematic, which uses a operational amplifier to turn on a n-channel mosfet when the night comes. I used a article from internet to make the connections of the unused operational ...
0
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1answer
52 views

Night Activated Switch

I draw a schematic which uses LM741 and IRF830. The main function of the schematic is to light up a few leds (which consumes about 100mA in total) when the night comes. Please have a look at the ...
5
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2answers
904 views

LM358N single supply does not reach GND

According to LM358 datasheet from TI it should be capable to reach GND when operated from a single power supply in linear mode. Thus I have decided to use it as input buffer to an ADC as shown: with ...
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1answer
40 views

What are alternative ICs for MC33274? [closed]

I'm using MPX2100dp pressure sensor for my project. I learnt that using MC33274 quad opamp can be used for making instrumentation amplifier. This IC is not available in local stores where I live. So I ...
0
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1answer
132 views

Transimpedance amplifier transfer function

I am learning analog design. I am trying to understand transimpedance amplifier using Op-Amp. Here is my transfer function. My understanding is assuming Node Va as virtual group I got (Vout= -Iin*Rg) ...
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1answer
62 views

My non-inverting amplifing circuit is always giving constant output values

I need to amplify voltages from range of -5mV/5mV to voltages of range -5V/5V. So I used circuit from the image. LF356N I decided to check if it is working by connecting it to Arduino Uno to simulate ...
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5answers
713 views

Is transistor in cutoff?

In the following circuit, consider the op-amp to be ideal (gain = ∞ , input resistance = ∞) and transistor beta is 20 A/A Initially I was using virtual ground concept here but in the given answer ...