Skip to main content

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.

1,051 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
5 votes
0 answers
1k views

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 ...
Sylvia's user avatar
  • 51
5 votes
0 answers
838 views

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 ...
maseeoo's user avatar
  • 53
4 votes
0 answers
104 views

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 ...
C-137's user avatar
  • 91
4 votes
0 answers
88 views

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 &...
Eduardo Ramírez Gómez's user avatar
4 votes
1 answer
127 views

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 ...
GNZ's user avatar
  • 1,729
4 votes
0 answers
307 views

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, ...
lobis's user avatar
  • 41
4 votes
0 answers
139 views

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 ...
George's user avatar
  • 91
4 votes
0 answers
194 views

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 ...
1N4001's user avatar
  • 163
4 votes
1 answer
121 views

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 ...
Ed Mcc's user avatar
  • 41
4 votes
0 answers
105 views

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 ...
Ken Shirriff's user avatar
  • 2,834
4 votes
0 answers
1k views

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 ...
kakeh's user avatar
  • 614
4 votes
0 answers
1k views

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 ...
scanny's user avatar
  • 7,132
4 votes
0 answers
2k views

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 ...
nesslersreagent's user avatar
4 votes
1 answer
133 views

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 ...
user avatar
3 votes
1 answer
45 views

Using Laplace transform to solve integrator circuit

I need to find Vout in time domain for below circuit. Here's my attempt, using Laplace transform. $$V_{in}(t) = V_0 \sin(\omega t)$$ From the above equation, Vin in s-domain is then: $$V_{in}(s)=V_0\...
user97662's user avatar
  • 273
3 votes
1 answer
109 views

Is it possible to achieve a square root analog filter?

I am attempting to create a (3/2)th-order active low-pass filter circuit, with a zero[es] at ω=10000 and pole[s] at ω=100. The only way I can think to do this is to simply cascade three simple first-...
Jonas Fletcher's user avatar
3 votes
0 answers
73 views

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 ...
Hugoagogo's user avatar
  • 2,445
3 votes
0 answers
68 views

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....
tac's user avatar
  • 335
3 votes
0 answers
121 views

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 ...
Idix's user avatar
  • 51
3 votes
0 answers
97 views

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 ...
Hyp's user avatar
  • 877
3 votes
0 answers
134 views

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 ...
coolyfrost's user avatar
3 votes
0 answers
314 views

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 ...
Eric Dahl's user avatar
  • 161
3 votes
0 answers
4k views

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 ...
BroomHilda's user avatar
3 votes
0 answers
1k views

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 ...
MrBit's user avatar
  • 2,013
3 votes
0 answers
419 views

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 ...
M2T156's user avatar
  • 137
3 votes
0 answers
296 views

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 ...
pr871's user avatar
  • 1,167
3 votes
0 answers
1k views

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 ...
Bud's user avatar
  • 389
3 votes
0 answers
822 views

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'...
user2268171's user avatar
3 votes
0 answers
752 views

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 ...
user135156's user avatar
3 votes
0 answers
450 views

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 ...
zacharoni16's user avatar
3 votes
1 answer
206 views

Protecting unpowered op-amp, or how can I use 12V to switch 3.3V?

I'm designing a Eurorack synthesizer module which includes an MCU, DAC (TI DAC8565), and TL074 op-amp for scaling and buffering the DAC output. In normal operation the module will operate from a +/-...
Russell Borogove's user avatar
3 votes
1 answer
939 views

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 ...
Joe of Loath's user avatar
2 votes
0 answers
80 views

Advice on active line-level audio mixer using a single supply rail

A few years ago a asked a question about an active audio (line level) mixer I wanted to make. I got some advice about how to run it off a single supply to make things easier and I was hoping to come ...
Jaska's user avatar
  • 77
2 votes
1 answer
74 views

Current slew rate specification of op-amps?

I know that slew rate specifies how fast the output voltage of an op-amp can change. But is there a measure that specifies how fast the output current of op-amps can change? I need this information ...
Mustafa Turhan's user avatar
2 votes
2 answers
141 views

I designed an opamp, any additions on how to make it better? (Closer to ideal opamp)

I'm not very good at electronics, but after learning for a bit, I designed a bare minimum opamp which has a differential amplifier and a Darlington NPN amplifier. Here is a picture: I thought about ...
TheAmplifier's user avatar
2 votes
2 answers
87 views

Dual Rail Reverse Protection Circuit for OP AMP inputs

Is there a way to resolve this? When wrong polarities is applied,then I wanted no voltage or current flowing towards the OP Amp. Thanks!!
HuracanWind's user avatar
2 votes
2 answers
127 views

How to determine the bandwidth of an op-amp in this case?

Regarding a TIA amplifier such as below: If IPD is a pulsed current produced by the photodiode and if the pulse width is 1 ns, what bandwidth of op-amp would be necessary? EDIT: I also don't care ...
GNZ's user avatar
  • 1,729
2 votes
1 answer
76 views

How can I calculate the resistance-capacitance values in an analog computer model?

This is the circuit design for this differential equation: $$\frac{d^2V_o(t)}{dt^2}+2\frac{dV_o(t)}{dt}+11 V_o(t)=V_i$$ Capacitor and resistor values don't add up for this circuit. How should I change ...
Efe kaptan's user avatar
2 votes
0 answers
74 views

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 ...
ViperJuice's user avatar
2 votes
0 answers
96 views

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 ...
Vitaliy Petliakivskyi's user avatar
2 votes
0 answers
61 views

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 ...
daniel's user avatar
  • 31
2 votes
1 answer
88 views

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 ...
Teena's user avatar
  • 101
2 votes
0 answers
51 views

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. ...
Elan's user avatar
  • 21
2 votes
0 answers
133 views

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 ...
Raphael's user avatar
  • 121
2 votes
0 answers
63 views

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 ...
Josef A's user avatar
  • 21
2 votes
1 answer
149 views

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 ...
Kishore Kumar S's user avatar
2 votes
0 answers
183 views

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- ...
Kishore Kumar S's user avatar
2 votes
0 answers
75 views

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 ...
peter's user avatar
  • 99
2 votes
1 answer
271 views

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 ...
flamezdude's user avatar
2 votes
0 answers
252 views

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 ...
Andrew Rusell's user avatar

1
2 3 4 5
22