Questions tagged [operational-amplifier]
Questions relating to the construction and applications of operational amplifiers, which are DC-coupled, high-gain electronic voltage amplifiers with a differential input and, usually, a single-ended output.
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What is the upper frequency limit for an op-amp integrator?
I'm designing a circuit to process a di/dt signal. As the input is the differential of the measured current, I have to integrate the voltage to provide a representation of the current. The duration of ...
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765
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PIN Photodiode gamma detection amplifier circuit - rectangular wave output
I've been working on a project recently, where I need to build a device which detects gamma radiation and can be used for gamma spectroscopy. I've done some research and found many interesting ways of ...
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How to interpret this depiction of an op-amp circuit?
I haven't used/seen this type of op-amp depiction before, so I'm having trouble understanding it. The research paper (linked below) says that this is an AD844AN chip, but even after looking through ...
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Circuit with resistance equal to input resistance
I want to use a digital potentiometer, however, the digital potentiometer has a power limit, which means I can't apply the voltage for my application.
I am looking for a circuit which functions as an &...
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1
answer
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Current source circuit components
I want to make a constant current driver for a laser diode (500 mA max.) based on the circuit shown below:
Here is my version:
In my case D2 and D3 represent the laser diode. There is a NC relay and ...
- 1,638
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Ultra-fast driver circuit for low-power LED
The goal is to drive a low power LED at a very high frequency, with pulses of ~10-100ns width in order to produce a very narrow burst of light. The pulses do not need to be closely packed together, ...
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128
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Nodal Analysis of an Inverting Operational Amplifier
I am trying to derive the closed-loop gain of a basic Inverting Op-Amp circuit using nodal analysis and the model that includes its non-ideal parameters. The equation I derived is incorrect, and it's ...
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Fixing overshoot in current regulation of AC electronic load
My AC electronic load (previous question here) shall have a constant-current mode. It is being simulated in LTspice.
@devnull helped design the circuit for AC loads, but for simplicity's sake in the ...
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4
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Dual supply op-amp, 0V on input yet small voltage on the out
I've been working on a constant current source design and have come up with the schematic below (heavily inspired from the LTC6082 datasheet), however, there is a small issue. When my input voltage is ...
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Audio amp IC: how does this output stage work?
I'm looking at an audio amplifier integrated circuit and the output stage seems a bit unusual. Has anyone seen this style of output stage, and does it have a name? And can anyone fill in the details ...
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Complete Noise Analysis: to find the minimum detectable signal of a TIA
Problem Statement:
my aim is to digitalize a 10ns narrow pulse coming from a photo diode with current ranging from 10nA-70mA, as its impossible to cover this dynamic range of >60dB using a single TIA ...
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Deriving PI controller transfer function when input is reversed
I'm developing the compensator for the linear DC Bench Power Supply I'm
designing.
As I've come to deriving the transfer function for the op amp-based
compensator, I realize I've been depending on a ...
- 7,082
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100kHz active filter design
I am designing a basic 100kHz active bandpass filter using opamps (LF353). I am only interested in receiving the 100kHz frequency (might drift a few kHz) from my input signal. I have used a basic ...
4
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Output voltage not stable - What is compensation with respect to DC-DC (buck converter)?
EDITS:
Input voltage range: 24V to 48V.
Changing the load current from 0.38A to 1.018A increases the mean output voltage from 12.779V to 13.26V. The supply should be producing 12.5V.
I'm using this ...
user220456
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Op-Amp Current Flow through inputs
I am trying to troubleshoot a relatively straightforward op-amp circuit where I am running into unusual behavior where current is flowing into or out of the input terminal of my op-amp.
The below ...
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Active load and current source purpose on NE5532
I'm trying to do some reverse engineering on the NE5532 schematic, but I can't understand how is designed the current source for the first stage. What I want to analyze now is in yellow on the picture....
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How does this capacitance measurement op-amp circuit work?
I'm studying this scientific paper where a capacitance measurement is done with the circuit shown at page 3. For simplicity I reported it here:
A sinusoidal signal is applied at the input through a ...
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Stability simulation - breaking the loop for a MOSFET - op-amp current source
The task at hand is to create a voltage controlled current source of 60 mA driving a valve coil (64 mH, 139 Ω). I am aware the MOSFET used is insufficient powerwise; it was a quick attempt to have a ...
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An amplifier that can output 40..50 V at around 15 MHz
I'm trying to build something to amplify a signal to produce a 40 V output at 15 MHz.
I haven't been successful in finding an opamp that can both output at these voltages while also not dropping the ...
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Wheatstone bridge with 3 op amps breadboard help
I have a wheatstone bridge like the following:
I then want to connect it to a couple of op-amps:
I tried doing it like this:
Op-amp pinout:
However, I can't seem to get it to work. Have i ...
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How to represent a microphone using a voltage dependent current source in LTspice?
I am using the following schematic and I'm trying to simulate it in LTspice but I am not sure how to represent the microphone. My instructor said I should use a voltage dependent current source but I ...
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Need help with an IR demodulation circuit
I'm trying to reverse engineer a PCB and made a schematic.
The bad thing is I only have PCB images from both sides, not the actual PCB. This PCB is used to detect a very small black object spinning at ...
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What is the definition of "the loading of feedback network on the input/output side"?
There is the following example:
simulate this circuit – Schematic created using CircuitLab
Its loading of the feedback network on the input side is 40kohm in series. Its loading of feedback ...
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Comparator with hysteresis calculation
I'm trying to calculate the hysteresis of the comparator using currents but something isn't right. I'd like a little help to find the hysteresis thresholds without the simplified equations.
simulate ...
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Transimpedance AMP, Active HPF, phototransistor
So this is the part where I would like the phototransistor (TEMT6000X01) to be able to clearly capture an LED with a frequency flashing on and off at 1kHz. So what I have here is a transimpedance ...
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CA3140 wideband output amplifier
The following circuit is nearly exactly what I need for the output stage of my function generator:
datasheet: https://www.renesas.com/us/en/www/doc/datasheet/ca3140-a.pdf
What I don't understand is ...
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Op-amp circuit stability (LTspice)
I want to study the stability of my op-amp circuit with LTspice. I found this video as tutorial: tutorial on phase margin
I did the simulation with closed and open loop as suggested and got the ...
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3
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2
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954
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Transimpedance amplifier calculating feedback capacitor
What is the correct way to calculate \$C_F\$ of the transimpedance amplifier? Since I have seen two different documents, and each has a different way to calculate it.
These two documents are:
Akshay ...
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Comparing sine wave and triangular for spwm using comparator
i am trying to generate sinusoidal PWM by comparing sine and triangular wave.
First i just tried to compare sine wave with reference voltage in order to check the working of op-amp. I get a problem ...
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PWM to synth control voltage improvements
Just built this little circuit to control my Moog Werkstatt. The plan is to make a MIDI-to-CV converter and add more CV outputs and of course a GATE output later. But before going further, I thought I'...
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Piezoelectric transducer impedance and phase measurement
I have a circuit comprising of LT1210 current feedback amplifier (supply voltage = +/-15V, gain = 4) and its output is connected to a transformer (RM10 N97) with N=16.6 (150/9) which is further ...
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Finding the transfer function of an op-amp filter circuit
I have the following third-order filter circuit:
simulate this circuit – Schematic created using CircuitLab
And I know that the transfer function looks like:
$$\mathscr{H}\left(\text{s}\right)=\...
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zero an accelerometer with opamp
I have a KXPS5-3157 Accelerometer, that outputs 0.330 to 2.97 VDC
http://www.futurebots.com/3157.pdf
The zero-G offset is 1.65VDC (VCC/2)
1G of gravity = 1.65VDC + 0.440 = 2.09 volts = ZERO to ...
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870
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Single supply op amp with input attenuator
I'm designing a guitar headphone amplifier that uses a single supply op-amp as the output stage to the headphones. I'm using a potentiometer after the final JFET stage and before the op-amps as a ...
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How to ramp a bi-polar Return to Zero (RZ) digital waveform
I am using a Raspberry Pi Pico and a few op-amps and resistors to implement an ARINC 429 transmitter. ARINC 429 is a bipolar RZ serial communication protocol commonly used in avionics. See the image ...
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OpAmp Selection | Sine Wave Amplifier: 30 MHz, 30Vpp with 15V offset
I am currently working on amplifying the output sine wave of the TG5011 professional signal generator. Below are the specifications for the amplifier I am aiming to create:
Power Supply: A single ...
2
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0
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Type 3 compensator with opamp compare calculation/simu and measured difference
I'm designing a type 3 compensator with an opamp for a flyback which is operating in a constant voltage mode.
Therefore I measured the plant and started to design a suitable type 3 compensator to ...
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2
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1
answer
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Introducing RC Filter to reduce noise
I have designed a constant current circuit using an opamp.
If I want to implement an RC filter to reduce the noise, where can I add?
Option1: I am planning to add between the inverting terminal and ...
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Adding programmable current limiting to an MP4688 LED driver
I'm trying to build a high quality constant current LED driver, with programmable current limit, and high frequency (20kHz) PWM dimming. The MP4688 (and MP2480) looked like they might fit the bill. ...
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Laser detector circuit with ambient light rejection
I recently asked how to best detect dropped balls via laser detection.
Someone suggested ambient light rejection by modulating the laser and then filtering the photodetector input for that signal.
I ...
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Why is connecting an analog servo distorting this PWM-wave?
I'm working on a project where I'm trying to steer an analog servo using a PWM-wave generated by this circuit. I found the circuit design from this article. It consists of three operational amplifiers ...
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How to design an opamp circuit for reactive load
I have an OPA548 IC which is a high-power op-amp. I am using it in non-inverting amplifier configuration as shown in the schematic.
The input signal is a ramp signal with low voltage 0.1 V and high ...
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Op-amp gives attenuated output
I am using an OPA547 high voltage and high current op-amp.
V+ = 15 V
V- = GND or -15 V
Ilim is shorted with V-
Vout has a fb resistor of 1K. The output load is a 50-ohm resistor
Vin+ = 0 V (GND)
Vin- ...
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AD826 low gain after around 1MHz
I am using AD826 op amp to convert differential current sinked DAC output operating at 50 mega samples per second. DAC is fed a 3MHz sine wave by a FPGA. Output of the DAC is fed to the opamp with ...
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1
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Op Amp Error Calculation
I am attempting to calculate the total error in an op amp (OPA2333 to be specific) that is used in a voltage sensing circuit. If I use the OPA2333 model in my SPICE circuit, are the errors already ...
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189
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MOSFET - Frequency response
I tried to do an exercise from my textbook where I have to discover the gain for mid frequencies of the MOSFET below, but I can't solve it. I got stuck at one point.
I drew the small signal ...
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Linear Analog Optocoupler Arrangements
For optocouplers with a second photodiode for feedback for linearization, what is the functional difference between the two positive input stage configurations below?
simulate this circuit – ...
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Current through op-amp feedback resistor
Image source: Fundamentals of Electric Circuits by Alexander and Sadiku. 5th Edition. Page 182
Can someone explain to me how 26.25uA is the correct answer here?
I am getting 11.25uA. If I assume ...
2
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1
answer
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Triangular waveform with low noise
I have a task to generate a triangular signal with variable amplitude and support.
The figure shows the type of signal and what parameters I want to change (“d” and “o”). Moreover, I need to change ...
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2
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Sanity check on this DAC reconstruction filter design
I've altered a reconstruction filter circuit to use the LTC728XT instead of the AD8608 op-amp used in the example circuit below. Is anyone able to see any issues with my attempt? This is being used as ...
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